diff --git a/pkgs/json_syntax_generator/lib/src/generator/helper_library.dart b/pkgs/json_syntax_generator/lib/src/generator/helper_library.dart
index 81b7b8687..137278d64 100644
--- a/pkgs/json_syntax_generator/lib/src/generator/helper_library.dart
+++ b/pkgs/json_syntax_generator/lib/src/generator/helper_library.dart
@@ -6,17 +6,27 @@
 ///
 /// This simplifies the code generator.
 const helperLib = r'''
-extension on Map<String, Object?> {
+class JsonReader {
+  /// The JSON Object this reader is reading.
+  final Map<String, Object?> json;
+
+  /// The path traversed by readers of the surrounding JSON.
+  ///
+  /// Contains [String] property keys and [int] indices.
+  ///
+  /// This is used to give more precise error messages.
+  final List<Object> path;
+
+  JsonReader(this.json, this.path);
+
   T get<T extends Object?>(String key) {
-    final value = this[key];
+    final value = json[key];
     if (value is T) return value;
+    final pathString = _jsonPathToString([key]);
     if (value == null) {
-      throw FormatException('No value was provided for required key: $key');
+      throw FormatException("No value was provided for '$pathString'.");
     }
-    throw FormatException(
-      'Unexpected value \'$value\' for key \'.$key\'. '
-      'Expected a $T.',
-    );
+    throwFormatException(value, T, [key]);
   }
 
   List<T> list<T extends Object?>(String key) =>
@@ -29,14 +39,13 @@ extension on Map<String, Object?> {
       };
 
   /// [List.cast] but with [FormatException]s.
-  static List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+  List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+    var index = 0;
     for (final value in list) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$list\' (${list.runtimeType}) for key \'.$key\'. '
-          'Expected a ${List<T>}.',
-        );
+        throwFormatException(value, T, [key, index]);
       }
+      index++;
     }
     return list.cast();
   }
@@ -60,16 +69,13 @@ extension on Map<String, Object?> {
       };
 
   /// [Map.cast] but with [FormatException]s.
-  static Map<String, T> _castMap<T extends Object?>(
+  Map<String, T> _castMap<T extends Object?>(
     Map<String, Object?> map_,
-    String key,
+    String parentKey,
   ) {
-    for (final value in map_.values) {
+    for (final MapEntry(:key, :value) in map_.entries) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$map_\' (${map_.runtimeType}) for key \'.$key\'.'
-          'Expected a ${Map<String, T>}.',
-        );
+        throwFormatException(value, T, [parentKey, key]);
       }
     }
     return map_.cast();
@@ -79,7 +85,7 @@ extension on Map<String, Object?> {
 
   List<String> stringList(String key) => list<String>(key);
 
-  Uri path(String key) => _fileSystemPathToUri(get<String>(key));
+  Uri path$(String key) => _fileSystemPathToUri(get<String>(key));
 
   Uri? optionalPath(String key) {
     final value = get<String?>(key);
@@ -102,6 +108,23 @@ extension on Map<String, Object?> {
     return Uri.file(path);
   }
 
+  String _jsonPathToString(List<Object> pathEnding) =>
+      [...path, ...pathEnding].join('.');
+
+  Never throwFormatException(
+    Object? value,
+    Type expectedType,
+    List<Object> pathExtension,
+  ) {
+    final pathString = _jsonPathToString(pathExtension);
+    throw FormatException(
+      "Unexpected value '$value' (${value.runtimeType}) for '$pathString'. "
+      'Expected a $expectedType.',
+    );
+  }
+}
+
+extension on Map<String, Object?> {
   void setOrRemove(String key, Object? value) {
     if (value == null) {
       remove(key);
diff --git a/pkgs/json_syntax_generator/lib/src/generator/normal_class_generator.dart b/pkgs/json_syntax_generator/lib/src/generator/normal_class_generator.dart
index 423f4bf6d..c33899737 100644
--- a/pkgs/json_syntax_generator/lib/src/generator/normal_class_generator.dart
+++ b/pkgs/json_syntax_generator/lib/src/generator/normal_class_generator.dart
@@ -72,7 +72,9 @@ class ClassGenerator {
     if (superclass != null) {
       buffer.writeln('''
 class $className extends $superclassName {
-  $className.fromJson(super.json) : super.fromJson();
+  $className.fromJson(super.json, {
+    super.path,
+  }) : super.fromJson();
 
   $className(${wrapBracesIfNotEmpty(constructorParams.join(', '))})
     : super(${superParams.join(',')}) 
@@ -102,9 +104,18 @@ class $className extends $superclassName {
 class $className {
   final Map<String, Object?> json;
 
-  $className.fromJson(this.json);
+  final List<Object> path;
 
-  $className(${wrapBracesIfNotEmpty(constructorParams.join(', '))}) : json = {} {
+  JsonReader get _reader => JsonReader(json, path);
+
+  $className.fromJson(this.json, {
+    this.path = const [],
+  });
+
+  $className(${wrapBracesIfNotEmpty(constructorParams.join(', '))})
+  : json = {},
+    path = const []
+  {
     ${constructorSetterCalls.join('\n    ')}
   }
 
diff --git a/pkgs/json_syntax_generator/lib/src/generator/property_generator.dart b/pkgs/json_syntax_generator/lib/src/generator/property_generator.dart
index 5ebd6b2cd..5e6e30803 100644
--- a/pkgs/json_syntax_generator/lib/src/generator/property_generator.dart
+++ b/pkgs/json_syntax_generator/lib/src/generator/property_generator.dart
@@ -95,7 +95,7 @@ class PropertyGenerator {
 
         buffer.writeln('''
 $dartType get $fieldName {
-  final jsonValue = json.get<$dartStringType>('$jsonKey'); $earlyReturn
+  final jsonValue = _reader.get<$dartStringType>('$jsonKey'); $earlyReturn
   return $classType.fromJson(jsonValue);
 }
 ''');
@@ -115,8 +115,8 @@ set $setterName($dartType value) {
         final jsonRead = required ? 'map\$' : 'optionalMap';
         buffer.writeln('''
 $dartType get $fieldName {
-  final jsonValue = json.$jsonRead('$jsonKey'); $earlyReturn
-  return $classType.fromJson(jsonValue);
+  final jsonValue = _reader.$jsonRead('$jsonKey'); $earlyReturn
+  return $classType.fromJson(jsonValue, path: [...path, '$jsonKey']);
 }
 ''');
         if (!property.isOverride) {
@@ -142,7 +142,7 @@ set $setterName($dartType value) {
     final fieldName = property.name;
 
     buffer.writeln('''
-$dartType get $fieldName => json.get<$dartType>('$jsonKey');
+$dartType get $fieldName => _reader.get<$dartType>('$jsonKey');
 
 set $setterName($dartType value) {
   json.setOrRemove('$jsonKey', value);
@@ -169,7 +169,7 @@ set $setterName($dartType value) {
       case MapDartType():
         buffer.writeln('''
 $dartType get $fieldName =>
-  json.optionalMap<${dartType.valueType}>('$jsonKey');
+  _reader.optionalMap<${dartType.valueType}>('$jsonKey');
 
 set $setterName($dartType value) {
   json.setOrRemove('$jsonKey', value);
@@ -181,17 +181,22 @@ set $setterName($dartType value) {
         final typeName = itemType.toString();
         buffer.writeln('''
 $dartType get $fieldName {
-  final map_ = json.optionalMap('$jsonKey');
-  if(map_ == null){
+  final jsonValue = _reader.optionalMap('$jsonKey');
+  if (jsonValue == null) {
     return null;
   }
-  return {
-    for (final MapEntry(:key, :value) in map_.entries)
-      key : [
-        for (final item in value as List<Object?>)
-          $typeName.fromJson(item as $jsonObjectDartType)
-      ],
-  };
+  final result = <String, List<Asset>>{};
+  for (final MapEntry(:key, :value) in jsonValue.entries) {
+    var index = 0;
+    result[key] = [
+      for (final item in value as List<Object?>)
+        $typeName.fromJson(
+          item as $jsonObjectDartType,
+          path: [...path, key, index++],
+        ),
+    ];
+  }
+  return result;
 }
 
 set $setterName($dartType value) {
@@ -214,7 +219,7 @@ set $setterName($dartType value) {
           case 'Object':
             if (valueType.isNullable) {
               buffer.writeln('''
-$dartType get $fieldName => json.optionalMap('$jsonKey');
+$dartType get $fieldName => _reader.optionalMap('$jsonKey');
 
 set $setterName($dartType value) {
   json.setOrRemove('$jsonKey', value);
@@ -251,8 +256,16 @@ set $setterName($dartType value) {
           throw UnimplementedError('Expected an optional property.');
         }
         buffer.writeln('''
-$dartType get $fieldName =>
-    json.optionalListParsed('$jsonKey', (e) => $typeName.fromJson(e as Map<String, Object?>));
+$dartType get $fieldName {
+  var index = 0;
+  return _reader.optionalListParsed(
+    '$jsonKey',
+    (e) => $typeName.fromJson(
+      e as Map<String, Object?>,
+      path: [...path, '$jsonKey', index++],
+    ),
+  );
+}
 
 set $setterName($dartType value) {
   if (value == null) {
@@ -273,7 +286,7 @@ set $setterName($dartType value) {
             final jsonRead = required ? 'stringList' : 'optionalStringList';
             final setter = setOrRemove(dartType, jsonKey);
             buffer.writeln('''
-$dartType get $fieldName => json.$jsonRead('$jsonKey');
+$dartType get $fieldName => _reader.$jsonRead('$jsonKey');
 
 set $setterName($dartType value) {
   $setter
@@ -288,7 +301,7 @@ set $setterName($dartType value) {
         final jsonRead = required ? 'pathList' : 'optionalPathList';
         final setter = setOrRemove(dartType, jsonKey, '.toJson()');
         buffer.writeln('''
-$dartType get $fieldName => json.$jsonRead('$jsonKey');
+$dartType get $fieldName => _reader.$jsonRead('$jsonKey');
 
 set $setterName($dartType value) {
   $setter
@@ -310,10 +323,10 @@ set $setterName($dartType value) {
   ) {
     final fieldName = property.name;
     final required = property.isRequired;
-    final jsonRead = required ? 'path' : 'optionalPath';
+    final jsonRead = required ? r'path$' : 'optionalPath';
     final setter = setOrRemove(dartType, jsonKey, '.toFilePath()');
     buffer.writeln('''
-$dartType get $fieldName => json.$jsonRead('$jsonKey');
+$dartType get $fieldName => _reader.$jsonRead('$jsonKey');
 
 set $setterName($dartType value) {
   $setter
diff --git a/pkgs/native_assets_cli/lib/src/code_assets/c_compiler_config.dart b/pkgs/native_assets_cli/lib/src/code_assets/c_compiler_config.dart
index d771d89c7..75668b6c4 100644
--- a/pkgs/native_assets_cli/lib/src/code_assets/c_compiler_config.dart
+++ b/pkgs/native_assets_cli/lib/src/code_assets/c_compiler_config.dart
@@ -37,19 +37,6 @@ final class CCompilerConfig {
     WindowsCCompilerConfig? windows,
   }) : _windows = windows;
 
-  /// Constructs a [CCompilerConfig] from the given [json].
-  ///
-  /// The json is expected to be valid encoding obtained via
-  /// [CCompilerConfig.toJson].
-  factory CCompilerConfig.fromJson(Map<String, Object?> json) =>
-      CCompilerConfigSyntax.fromSyntax(syntax.CCompilerConfig.fromJson(json));
-
-  /// The json representation of this [CCompilerConfig].
-  ///
-  /// The returned json can be used in [CCompilerConfig.fromJson] to
-  /// obtain a [CCompilerConfig] again.
-  Map<String, Object?> toJson() => toSyntax().json;
-
   @override
   bool operator ==(Object other) {
     if (other is! CCompilerConfig) {
diff --git a/pkgs/native_assets_cli/lib/src/code_assets/code_asset.dart b/pkgs/native_assets_cli/lib/src/code_assets/code_asset.dart
index c67ed9b4c..4b88ba552 100644
--- a/pkgs/native_assets_cli/lib/src/code_assets/code_asset.dart
+++ b/pkgs/native_assets_cli/lib/src/code_assets/code_asset.dart
@@ -107,7 +107,10 @@ final class CodeAsset {
   factory CodeAsset.fromEncoded(EncodedAsset asset) {
     assert(asset.type == CodeAsset.type);
     final jsonMap = asset.encoding;
-    final syntaxNode = syntax.NativeCodeAsset.fromJson(jsonMap);
+    final syntaxNode = syntax.NativeCodeAsset.fromJson(
+      jsonMap,
+      path: asset.jsonPath ?? [],
+    );
     return CodeAsset._(
       id: syntaxNode.id,
       os: OSSyntax.fromSyntax(syntaxNode.os),
diff --git a/pkgs/native_assets_cli/lib/src/code_assets/config.dart b/pkgs/native_assets_cli/lib/src/code_assets/config.dart
index fb479f586..15fff042e 100644
--- a/pkgs/native_assets_cli/lib/src/code_assets/config.dart
+++ b/pkgs/native_assets_cli/lib/src/code_assets/config.dart
@@ -16,7 +16,7 @@ import 'syntax.g.dart' as syntax;
 /// to code assets (only available if code assets are supported).
 extension CodeAssetHookConfig on HookConfig {
   /// Code asset specific configuration.
-  CodeConfig get code => CodeConfig._fromJson(json);
+  CodeConfig get code => CodeConfig._fromJson(json, path);
 
   bool get buildCodeAssets => buildAssetTypes.contains(CodeAsset.type);
 }
@@ -41,8 +41,8 @@ extension CodeAssetLinkInput on LinkInputAssets {
 class CodeConfig {
   final syntax.CodeConfig _syntax;
 
-  CodeConfig._fromJson(Map<String, Object?> json)
-    : _syntax = syntax.Config.fromJson(json).code!;
+  CodeConfig._fromJson(Map<String, Object?> json, List<Object> path)
+    : _syntax = syntax.Config.fromJson(json, path: path).code!;
 
   /// The architecture the code code asset should be built for.
   ///
diff --git a/pkgs/native_assets_cli/lib/src/code_assets/syntax.g.dart b/pkgs/native_assets_cli/lib/src/code_assets/syntax.g.dart
index 388704285..a719c66e6 100644
--- a/pkgs/native_assets_cli/lib/src/code_assets/syntax.g.dart
+++ b/pkgs/native_assets_cli/lib/src/code_assets/syntax.g.dart
@@ -11,14 +11,18 @@ import 'dart:io';
 class AndroidCodeConfig {
   final Map<String, Object?> json;
 
-  AndroidCodeConfig.fromJson(this.json);
+  final List<Object> path;
 
-  AndroidCodeConfig({int? targetNdkApi}) : json = {} {
+  JsonReader get _reader => JsonReader(json, path);
+
+  AndroidCodeConfig.fromJson(this.json, {this.path = const []});
+
+  AndroidCodeConfig({int? targetNdkApi}) : json = {}, path = const [] {
     _targetNdkApi = targetNdkApi;
     json.sortOnKey();
   }
 
-  int? get targetNdkApi => json.get<int?>('target_ndk_api');
+  int? get targetNdkApi => _reader.get<int?>('target_ndk_api');
 
   set _targetNdkApi(int? value) {
     json.setOrRemove('target_ndk_api', value);
@@ -77,14 +81,18 @@ class Architecture {
 class Asset {
   final Map<String, Object?> json;
 
-  Asset.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
 
-  Asset({String? type}) : json = {} {
+  Asset.fromJson(this.json, {this.path = const []});
+
+  Asset({String? type}) : json = {}, path = const [] {
     _type = type;
     json.sortOnKey();
   }
 
-  String? get type => json.get<String?>('type');
+  String? get type => _reader.get<String?>('type');
 
   set _type(String? value) {
     json.setOrRemove('type', value);
@@ -95,7 +103,7 @@ class Asset {
 }
 
 class NativeCodeAsset extends Asset {
-  NativeCodeAsset.fromJson(super.json) : super.fromJson();
+  NativeCodeAsset.fromJson(super.json, {super.path}) : super.fromJson();
 
   NativeCodeAsset({
     Architecture? architecture,
@@ -130,7 +138,7 @@ class NativeCodeAsset extends Asset {
   }
 
   Architecture? get architecture {
-    final jsonValue = json.get<String?>('architecture');
+    final jsonValue = _reader.get<String?>('architecture');
     if (jsonValue == null) return null;
     return Architecture.fromJson(jsonValue);
   }
@@ -139,21 +147,21 @@ class NativeCodeAsset extends Asset {
     json.setOrRemove('architecture', value?.name);
   }
 
-  Uri? get file => json.optionalPath('file');
+  Uri? get file => _reader.optionalPath('file');
 
   set _file(Uri? value) {
     json.setOrRemove('file', value?.toFilePath());
   }
 
-  String get id => json.get<String>('id');
+  String get id => _reader.get<String>('id');
 
   set _id(String value) {
     json.setOrRemove('id', value);
   }
 
   LinkMode get linkMode {
-    final jsonValue = json.map$('link_mode');
-    return LinkMode.fromJson(jsonValue);
+    final jsonValue = _reader.map$('link_mode');
+    return LinkMode.fromJson(jsonValue, path: [...path, 'link_mode']);
   }
 
   set _linkMode(LinkMode value) {
@@ -161,7 +169,7 @@ class NativeCodeAsset extends Asset {
   }
 
   OS get os {
-    final jsonValue = json.get<String>('os');
+    final jsonValue = _reader.get<String>('os');
     return OS.fromJson(jsonValue);
   }
 
@@ -182,7 +190,11 @@ extension NativeCodeAssetExtension on Asset {
 class CCompilerConfig {
   final Map<String, Object?> json;
 
-  CCompilerConfig.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  CCompilerConfig.fromJson(this.json, {this.path = const []});
 
   CCompilerConfig({
     required Uri ar,
@@ -191,7 +203,8 @@ class CCompilerConfig {
     List<String>? envScriptArguments,
     required Uri ld,
     Windows? windows,
-  }) : json = {} {
+  }) : json = {},
+       path = const [] {
     _ar = ar;
     _cc = cc;
     _envScript = envScript;
@@ -201,41 +214,41 @@ class CCompilerConfig {
     json.sortOnKey();
   }
 
-  Uri get ar => json.path('ar');
+  Uri get ar => _reader.path$('ar');
 
   set _ar(Uri value) {
     json['ar'] = value.toFilePath();
   }
 
-  Uri get cc => json.path('cc');
+  Uri get cc => _reader.path$('cc');
 
   set _cc(Uri value) {
     json['cc'] = value.toFilePath();
   }
 
-  Uri? get envScript => json.optionalPath('env_script');
+  Uri? get envScript => _reader.optionalPath('env_script');
 
   set _envScript(Uri? value) {
     json.setOrRemove('env_script', value?.toFilePath());
   }
 
   List<String>? get envScriptArguments =>
-      json.optionalStringList('env_script_arguments');
+      _reader.optionalStringList('env_script_arguments');
 
   set _envScriptArguments(List<String>? value) {
     json.setOrRemove('env_script_arguments', value);
   }
 
-  Uri get ld => json.path('ld');
+  Uri get ld => _reader.path$('ld');
 
   set _ld(Uri value) {
     json['ld'] = value.toFilePath();
   }
 
   Windows? get windows {
-    final jsonValue = json.optionalMap('windows');
+    final jsonValue = _reader.optionalMap('windows');
     if (jsonValue == null) return null;
-    return Windows.fromJson(jsonValue);
+    return Windows.fromJson(jsonValue, path: [...path, 'windows']);
   }
 
   set _windows(Windows? value) {
@@ -249,17 +262,26 @@ class CCompilerConfig {
 class Windows {
   final Map<String, Object?> json;
 
-  Windows.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  Windows.fromJson(this.json, {this.path = const []});
 
-  Windows({DeveloperCommandPrompt? developerCommandPrompt}) : json = {} {
+  Windows({DeveloperCommandPrompt? developerCommandPrompt})
+    : json = {},
+      path = const [] {
     _developerCommandPrompt = developerCommandPrompt;
     json.sortOnKey();
   }
 
   DeveloperCommandPrompt? get developerCommandPrompt {
-    final jsonValue = json.optionalMap('developer_command_prompt');
+    final jsonValue = _reader.optionalMap('developer_command_prompt');
     if (jsonValue == null) return null;
-    return DeveloperCommandPrompt.fromJson(jsonValue);
+    return DeveloperCommandPrompt.fromJson(
+      jsonValue,
+      path: [...path, 'developer_command_prompt'],
+    );
   }
 
   set _developerCommandPrompt(DeveloperCommandPrompt? value) {
@@ -273,22 +295,27 @@ class Windows {
 class DeveloperCommandPrompt {
   final Map<String, Object?> json;
 
-  DeveloperCommandPrompt.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  DeveloperCommandPrompt.fromJson(this.json, {this.path = const []});
 
   DeveloperCommandPrompt({required List<String> arguments, required Uri script})
-    : json = {} {
+    : json = {},
+      path = const [] {
     _arguments = arguments;
     _script = script;
     json.sortOnKey();
   }
 
-  List<String> get arguments => json.stringList('arguments');
+  List<String> get arguments => _reader.stringList('arguments');
 
   set _arguments(List<String> value) {
     json['arguments'] = value;
   }
 
-  Uri get script => json.path('script');
+  Uri get script => _reader.path$('script');
 
   set _script(Uri value) {
     json['script'] = value.toFilePath();
@@ -301,7 +328,11 @@ class DeveloperCommandPrompt {
 class CodeConfig {
   final Map<String, Object?> json;
 
-  CodeConfig.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  CodeConfig.fromJson(this.json, {this.path = const []});
 
   CodeConfig({
     AndroidCodeConfig? android,
@@ -311,7 +342,8 @@ class CodeConfig {
     MacOSCodeConfig? macOS,
     required Architecture targetArchitecture,
     required OS targetOs,
-  }) : json = {} {
+  }) : json = {},
+       path = const [] {
     _android = android;
     _cCompiler = cCompiler;
     _iOS = iOS;
@@ -323,9 +355,9 @@ class CodeConfig {
   }
 
   AndroidCodeConfig? get android {
-    final jsonValue = json.optionalMap('android');
+    final jsonValue = _reader.optionalMap('android');
     if (jsonValue == null) return null;
-    return AndroidCodeConfig.fromJson(jsonValue);
+    return AndroidCodeConfig.fromJson(jsonValue, path: [...path, 'android']);
   }
 
   set _android(AndroidCodeConfig? value) {
@@ -333,9 +365,9 @@ class CodeConfig {
   }
 
   CCompilerConfig? get cCompiler {
-    final jsonValue = json.optionalMap('c_compiler');
+    final jsonValue = _reader.optionalMap('c_compiler');
     if (jsonValue == null) return null;
-    return CCompilerConfig.fromJson(jsonValue);
+    return CCompilerConfig.fromJson(jsonValue, path: [...path, 'c_compiler']);
   }
 
   set _cCompiler(CCompilerConfig? value) {
@@ -343,9 +375,9 @@ class CodeConfig {
   }
 
   IOSCodeConfig? get iOS {
-    final jsonValue = json.optionalMap('ios');
+    final jsonValue = _reader.optionalMap('ios');
     if (jsonValue == null) return null;
-    return IOSCodeConfig.fromJson(jsonValue);
+    return IOSCodeConfig.fromJson(jsonValue, path: [...path, 'ios']);
   }
 
   set _iOS(IOSCodeConfig? value) {
@@ -353,7 +385,7 @@ class CodeConfig {
   }
 
   LinkModePreference get linkModePreference {
-    final jsonValue = json.get<String>('link_mode_preference');
+    final jsonValue = _reader.get<String>('link_mode_preference');
     return LinkModePreference.fromJson(jsonValue);
   }
 
@@ -362,9 +394,9 @@ class CodeConfig {
   }
 
   MacOSCodeConfig? get macOS {
-    final jsonValue = json.optionalMap('macos');
+    final jsonValue = _reader.optionalMap('macos');
     if (jsonValue == null) return null;
-    return MacOSCodeConfig.fromJson(jsonValue);
+    return MacOSCodeConfig.fromJson(jsonValue, path: [...path, 'macos']);
   }
 
   set _macOS(MacOSCodeConfig? value) {
@@ -372,7 +404,7 @@ class CodeConfig {
   }
 
   Architecture get targetArchitecture {
-    final jsonValue = json.get<String>('target_architecture');
+    final jsonValue = _reader.get<String>('target_architecture');
     return Architecture.fromJson(jsonValue);
   }
 
@@ -381,7 +413,7 @@ class CodeConfig {
   }
 
   OS get targetOs {
-    final jsonValue = json.get<String>('target_os');
+    final jsonValue = _reader.get<String>('target_os');
     return OS.fromJson(jsonValue);
   }
 
@@ -396,17 +428,21 @@ class CodeConfig {
 class Config {
   final Map<String, Object?> json;
 
-  Config.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  Config.fromJson(this.json, {this.path = const []});
 
-  Config({CodeConfig? code}) : json = {} {
+  Config({CodeConfig? code}) : json = {}, path = const [] {
     this.code = code;
     json.sortOnKey();
   }
 
   CodeConfig? get code {
-    final jsonValue = json.optionalMap('code');
+    final jsonValue = _reader.optionalMap('code');
     if (jsonValue == null) return null;
-    return CodeConfig.fromJson(jsonValue);
+    return CodeConfig.fromJson(jsonValue, path: [...path, 'code']);
   }
 
   set code(CodeConfig? value) {
@@ -421,21 +457,27 @@ class Config {
 class IOSCodeConfig {
   final Map<String, Object?> json;
 
-  IOSCodeConfig.fromJson(this.json);
+  final List<Object> path;
 
-  IOSCodeConfig({String? targetSdk, int? targetVersion}) : json = {} {
+  JsonReader get _reader => JsonReader(json, path);
+
+  IOSCodeConfig.fromJson(this.json, {this.path = const []});
+
+  IOSCodeConfig({String? targetSdk, int? targetVersion})
+    : json = {},
+      path = const [] {
     _targetSdk = targetSdk;
     _targetVersion = targetVersion;
     json.sortOnKey();
   }
 
-  String? get targetSdk => json.get<String?>('target_sdk');
+  String? get targetSdk => _reader.get<String?>('target_sdk');
 
   set _targetSdk(String? value) {
     json.setOrRemove('target_sdk', value);
   }
 
-  int? get targetVersion => json.get<int?>('target_version');
+  int? get targetVersion => _reader.get<int?>('target_version');
 
   set _targetVersion(int? value) {
     json.setOrRemove('target_version', value);
@@ -448,14 +490,18 @@ class IOSCodeConfig {
 class LinkMode {
   final Map<String, Object?> json;
 
-  LinkMode.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  LinkMode.fromJson(this.json, {this.path = const []});
 
-  LinkMode({required String type}) : json = {} {
+  LinkMode({required String type}) : json = {}, path = const [] {
     _type = type;
     json.sortOnKey();
   }
 
-  String get type => json.get<String>('type');
+  String get type => _reader.get<String>('type');
 
   set _type(String value) {
     json.setOrRemove('type', value);
@@ -466,7 +512,8 @@ class LinkMode {
 }
 
 class DynamicLoadingBundleLinkMode extends LinkMode {
-  DynamicLoadingBundleLinkMode.fromJson(super.json) : super.fromJson();
+  DynamicLoadingBundleLinkMode.fromJson(super.json, {super.path})
+    : super.fromJson();
 
   DynamicLoadingBundleLinkMode() : super(type: 'dynamic_loading_bundle');
 
@@ -482,7 +529,8 @@ extension DynamicLoadingBundleLinkModeExtension on LinkMode {
 }
 
 class DynamicLoadingExecutableLinkMode extends LinkMode {
-  DynamicLoadingExecutableLinkMode.fromJson(super.json) : super.fromJson();
+  DynamicLoadingExecutableLinkMode.fromJson(super.json, {super.path})
+    : super.fromJson();
 
   DynamicLoadingExecutableLinkMode()
     : super(type: 'dynamic_loading_executable');
@@ -500,7 +548,8 @@ extension DynamicLoadingExecutableLinkModeExtension on LinkMode {
 }
 
 class DynamicLoadingProcessLinkMode extends LinkMode {
-  DynamicLoadingProcessLinkMode.fromJson(super.json) : super.fromJson();
+  DynamicLoadingProcessLinkMode.fromJson(super.json, {super.path})
+    : super.fromJson();
 
   DynamicLoadingProcessLinkMode() : super(type: 'dynamic_loading_process');
 
@@ -516,7 +565,8 @@ extension DynamicLoadingProcessLinkModeExtension on LinkMode {
 }
 
 class DynamicLoadingSystemLinkMode extends LinkMode {
-  DynamicLoadingSystemLinkMode.fromJson(super.json) : super.fromJson();
+  DynamicLoadingSystemLinkMode.fromJson(super.json, {super.path})
+    : super.fromJson();
 
   DynamicLoadingSystemLinkMode({required Uri uri})
     : super(type: 'dynamic_loading_system') {
@@ -531,7 +581,7 @@ class DynamicLoadingSystemLinkMode extends LinkMode {
     json.sortOnKey();
   }
 
-  Uri get uri => json.path('uri');
+  Uri get uri => _reader.path$('uri');
 
   set _uri(Uri value) {
     json['uri'] = value.toFilePath();
@@ -549,7 +599,7 @@ extension DynamicLoadingSystemLinkModeExtension on LinkMode {
 }
 
 class StaticLinkMode extends LinkMode {
-  StaticLinkMode.fromJson(super.json) : super.fromJson();
+  StaticLinkMode.fromJson(super.json, {super.path}) : super.fromJson();
 
   StaticLinkMode() : super(type: 'static');
 
@@ -606,14 +656,18 @@ class LinkModePreference {
 class MacOSCodeConfig {
   final Map<String, Object?> json;
 
-  MacOSCodeConfig.fromJson(this.json);
+  final List<Object> path;
 
-  MacOSCodeConfig({int? targetVersion}) : json = {} {
+  JsonReader get _reader => JsonReader(json, path);
+
+  MacOSCodeConfig.fromJson(this.json, {this.path = const []});
+
+  MacOSCodeConfig({int? targetVersion}) : json = {}, path = const [] {
     _targetVersion = targetVersion;
     json.sortOnKey();
   }
 
-  int? get targetVersion => json.get<int?>('target_version');
+  int? get targetVersion => _reader.get<int?>('target_version');
 
   set _targetVersion(int? value) {
     json.setOrRemove('target_version', value);
@@ -660,17 +714,27 @@ class OS {
   String toString() => name;
 }
 
-extension on Map<String, Object?> {
+class JsonReader {
+  /// The JSON Object this reader is reading.
+  final Map<String, Object?> json;
+
+  /// The path traversed by readers of the surrounding JSON.
+  ///
+  /// Contains [String] property keys and [int] indices.
+  ///
+  /// This is used to give more precise error messages.
+  final List<Object> path;
+
+  JsonReader(this.json, this.path);
+
   T get<T extends Object?>(String key) {
-    final value = this[key];
+    final value = json[key];
     if (value is T) return value;
+    final pathString = _jsonPathToString([key]);
     if (value == null) {
-      throw FormatException('No value was provided for required key: $key');
+      throw FormatException("No value was provided for '$pathString'.");
     }
-    throw FormatException(
-      'Unexpected value \'$value\' for key \'.$key\'. '
-      'Expected a $T.',
-    );
+    throwFormatException(value, T, [key]);
   }
 
   List<T> list<T extends Object?>(String key) =>
@@ -683,14 +747,13 @@ extension on Map<String, Object?> {
       };
 
   /// [List.cast] but with [FormatException]s.
-  static List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+  List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+    var index = 0;
     for (final value in list) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$list\' (${list.runtimeType}) for key \'.$key\'. '
-          'Expected a ${List<T>}.',
-        );
+        throwFormatException(value, T, [key, index]);
       }
+      index++;
     }
     return list.cast();
   }
@@ -714,16 +777,13 @@ extension on Map<String, Object?> {
       };
 
   /// [Map.cast] but with [FormatException]s.
-  static Map<String, T> _castMap<T extends Object?>(
+  Map<String, T> _castMap<T extends Object?>(
     Map<String, Object?> map_,
-    String key,
+    String parentKey,
   ) {
-    for (final value in map_.values) {
+    for (final MapEntry(:key, :value) in map_.entries) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$map_\' (${map_.runtimeType}) for key \'.$key\'.'
-          'Expected a ${Map<String, T>}.',
-        );
+        throwFormatException(value, T, [parentKey, key]);
       }
     }
     return map_.cast();
@@ -733,7 +793,7 @@ extension on Map<String, Object?> {
 
   List<String> stringList(String key) => list<String>(key);
 
-  Uri path(String key) => _fileSystemPathToUri(get<String>(key));
+  Uri path$(String key) => _fileSystemPathToUri(get<String>(key));
 
   Uri? optionalPath(String key) {
     final value = get<String?>(key);
@@ -756,6 +816,23 @@ extension on Map<String, Object?> {
     return Uri.file(path);
   }
 
+  String _jsonPathToString(List<Object> pathEnding) =>
+      [...path, ...pathEnding].join('.');
+
+  Never throwFormatException(
+    Object? value,
+    Type expectedType,
+    List<Object> pathExtension,
+  ) {
+    final pathString = _jsonPathToString(pathExtension);
+    throw FormatException(
+      "Unexpected value '$value' (${value.runtimeType}) for '$pathString'. "
+      'Expected a $expectedType.',
+    );
+  }
+}
+
+extension on Map<String, Object?> {
   void setOrRemove(String key, Object? value) {
     if (value == null) {
       remove(key);
diff --git a/pkgs/native_assets_cli/lib/src/config.dart b/pkgs/native_assets_cli/lib/src/config.dart
index a285ab214..7ca9f3786 100644
--- a/pkgs/native_assets_cli/lib/src/config.dart
+++ b/pkgs/native_assets_cli/lib/src/config.dart
@@ -245,7 +245,10 @@ final class LinkInputBuilder extends HookInputBuilder {
 List<EncodedAsset> _parseAssets(List<syntax.Asset>? assets) =>
     assets == null
         ? []
-        : [for (final asset in assets) EncodedAsset.fromJson(asset.json)];
+        : [
+          for (final asset in assets)
+            EncodedAsset.fromJson(asset.json, asset.path),
+        ];
 
 sealed class HookOutput {
   /// The underlying json configuration of this [HookOutput].
@@ -587,6 +590,8 @@ final latestParsableVersion = Version(1, 7, 0);
 final class HookConfig {
   Map<String, Object?> get json => _syntax.json;
 
+  List<Object> get path => _syntax.path;
+
   final syntax.Config _syntax;
 
   /// The asset types that should be built by an invocation of a hook.
@@ -617,6 +622,9 @@ final class BuildConfig extends HookConfig {
   bool get linkingEnabled => _syntax.linkingEnabled;
 
   BuildConfig._(super.input)
-    : _syntax = syntax.BuildConfig.fromJson(input._syntax.config.json),
+    : _syntax = syntax.BuildConfig.fromJson(
+        input._syntax.config.json,
+        path: input._syntax.config.path,
+      ),
       super._();
 }
diff --git a/pkgs/native_assets_cli/lib/src/data_assets/syntax.g.dart b/pkgs/native_assets_cli/lib/src/data_assets/syntax.g.dart
index 7df687055..d88a736b2 100644
--- a/pkgs/native_assets_cli/lib/src/data_assets/syntax.g.dart
+++ b/pkgs/native_assets_cli/lib/src/data_assets/syntax.g.dart
@@ -11,14 +11,18 @@ import 'dart:io';
 class Asset {
   final Map<String, Object?> json;
 
-  Asset.fromJson(this.json);
+  final List<Object> path;
 
-  Asset({String? type}) : json = {} {
+  JsonReader get _reader => JsonReader(json, path);
+
+  Asset.fromJson(this.json, {this.path = const []});
+
+  Asset({String? type}) : json = {}, path = const [] {
     _type = type;
     json.sortOnKey();
   }
 
-  String? get type => json.get<String?>('type');
+  String? get type => _reader.get<String?>('type');
 
   set _type(String? value) {
     json.setOrRemove('type', value);
@@ -29,7 +33,7 @@ class Asset {
 }
 
 class DataAsset extends Asset {
-  DataAsset.fromJson(super.json) : super.fromJson();
+  DataAsset.fromJson(super.json, {super.path}) : super.fromJson();
 
   DataAsset({required Uri file, required String name, required String package})
     : super(type: 'data') {
@@ -52,19 +56,19 @@ class DataAsset extends Asset {
     json.sortOnKey();
   }
 
-  Uri get file => json.path('file');
+  Uri get file => _reader.path$('file');
 
   set _file(Uri value) {
     json['file'] = value.toFilePath();
   }
 
-  String get name => json.get<String>('name');
+  String get name => _reader.get<String>('name');
 
   set _name(String value) {
     json.setOrRemove('name', value);
   }
 
-  String get package => json.get<String>('package');
+  String get package => _reader.get<String>('package');
 
   set _package(String value) {
     json.setOrRemove('package', value);
@@ -80,17 +84,27 @@ extension DataAssetExtension on Asset {
   DataAsset get asDataAsset => DataAsset.fromJson(json);
 }
 
-extension on Map<String, Object?> {
+class JsonReader {
+  /// The JSON Object this reader is reading.
+  final Map<String, Object?> json;
+
+  /// The path traversed by readers of the surrounding JSON.
+  ///
+  /// Contains [String] property keys and [int] indices.
+  ///
+  /// This is used to give more precise error messages.
+  final List<Object> path;
+
+  JsonReader(this.json, this.path);
+
   T get<T extends Object?>(String key) {
-    final value = this[key];
+    final value = json[key];
     if (value is T) return value;
+    final pathString = _jsonPathToString([key]);
     if (value == null) {
-      throw FormatException('No value was provided for required key: $key');
+      throw FormatException("No value was provided for '$pathString'.");
     }
-    throw FormatException(
-      'Unexpected value \'$value\' for key \'.$key\'. '
-      'Expected a $T.',
-    );
+    throwFormatException(value, T, [key]);
   }
 
   List<T> list<T extends Object?>(String key) =>
@@ -103,14 +117,13 @@ extension on Map<String, Object?> {
       };
 
   /// [List.cast] but with [FormatException]s.
-  static List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+  List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+    var index = 0;
     for (final value in list) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$list\' (${list.runtimeType}) for key \'.$key\'. '
-          'Expected a ${List<T>}.',
-        );
+        throwFormatException(value, T, [key, index]);
       }
+      index++;
     }
     return list.cast();
   }
@@ -134,16 +147,13 @@ extension on Map<String, Object?> {
       };
 
   /// [Map.cast] but with [FormatException]s.
-  static Map<String, T> _castMap<T extends Object?>(
+  Map<String, T> _castMap<T extends Object?>(
     Map<String, Object?> map_,
-    String key,
+    String parentKey,
   ) {
-    for (final value in map_.values) {
+    for (final MapEntry(:key, :value) in map_.entries) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$map_\' (${map_.runtimeType}) for key \'.$key\'.'
-          'Expected a ${Map<String, T>}.',
-        );
+        throwFormatException(value, T, [parentKey, key]);
       }
     }
     return map_.cast();
@@ -153,7 +163,7 @@ extension on Map<String, Object?> {
 
   List<String> stringList(String key) => list<String>(key);
 
-  Uri path(String key) => _fileSystemPathToUri(get<String>(key));
+  Uri path$(String key) => _fileSystemPathToUri(get<String>(key));
 
   Uri? optionalPath(String key) {
     final value = get<String?>(key);
@@ -176,6 +186,23 @@ extension on Map<String, Object?> {
     return Uri.file(path);
   }
 
+  String _jsonPathToString(List<Object> pathEnding) =>
+      [...path, ...pathEnding].join('.');
+
+  Never throwFormatException(
+    Object? value,
+    Type expectedType,
+    List<Object> pathExtension,
+  ) {
+    final pathString = _jsonPathToString(pathExtension);
+    throw FormatException(
+      "Unexpected value '$value' (${value.runtimeType}) for '$pathString'. "
+      'Expected a $expectedType.',
+    );
+  }
+}
+
+extension on Map<String, Object?> {
   void setOrRemove(String key, Object? value) {
     if (value == null) {
       remove(key);
diff --git a/pkgs/native_assets_cli/lib/src/encoded_asset.dart b/pkgs/native_assets_cli/lib/src/encoded_asset.dart
index 959f3a6f0..39cf5d165 100644
--- a/pkgs/native_assets_cli/lib/src/encoded_asset.dart
+++ b/pkgs/native_assets_cli/lib/src/encoded_asset.dart
@@ -15,15 +15,23 @@ final class EncodedAsset {
   /// The json encoding of the asset.
   final Map<String, Object?> encoding;
 
-  EncodedAsset(this.type, this.encoding);
+  /// The path of this object in a larger JSON.
+  ///
+  /// If provided, used for more precise error messages.
+  final List<Object>? jsonPath;
+
+  EncodedAsset(this.type, this.encoding, {this.jsonPath});
 
   /// Decode an [EncodedAsset] from json.
-  factory EncodedAsset.fromJson(Map<String, Object?> json) {
+  factory EncodedAsset.fromJson(
+    Map<String, Object?> json, [
+    List<Object>? path,
+  ]) {
     final syntax_ = syntax.Asset.fromJson(json);
     return EncodedAsset(syntax_.type, {
       for (final key in json.keys)
         if (key != _typeKey) key: json[key],
-    });
+    }, jsonPath: path);
   }
 
   /// Encode this [EncodedAsset] tojson.
diff --git a/pkgs/native_assets_cli/lib/src/hook/syntax.g.dart b/pkgs/native_assets_cli/lib/src/hook/syntax.g.dart
index f57a03cd4..bb2b4492a 100644
--- a/pkgs/native_assets_cli/lib/src/hook/syntax.g.dart
+++ b/pkgs/native_assets_cli/lib/src/hook/syntax.g.dart
@@ -11,14 +11,18 @@ import 'dart:io';
 class Asset {
   final Map<String, Object?> json;
 
-  Asset.fromJson(this.json);
+  final List<Object> path;
 
-  Asset({required String type}) : json = {} {
+  JsonReader get _reader => JsonReader(json, path);
+
+  Asset.fromJson(this.json, {this.path = const []});
+
+  Asset({required String type}) : json = {}, path = const [] {
     _type = type;
     json.sortOnKey();
   }
 
-  String get type => json.get<String>('type');
+  String get type => _reader.get<String>('type');
 
   set _type(String value) {
     json.setOrRemove('type', value);
@@ -29,7 +33,7 @@ class Asset {
 }
 
 class BuildConfig extends Config {
-  BuildConfig.fromJson(super.json) : super.fromJson();
+  BuildConfig.fromJson(super.json, {super.path}) : super.fromJson();
 
   BuildConfig({required super.buildAssetTypes, required bool linkingEnabled})
     : super() {
@@ -44,7 +48,7 @@ class BuildConfig extends Config {
     json.sortOnKey();
   }
 
-  bool get linkingEnabled => json.get<bool>('linking_enabled');
+  bool get linkingEnabled => _reader.get<bool>('linking_enabled');
 
   set _linkingEnabled(bool value) {
     json.setOrRemove('linking_enabled', value);
@@ -55,7 +59,7 @@ class BuildConfig extends Config {
 }
 
 class BuildInput extends HookInput {
-  BuildInput.fromJson(super.json) : super.fromJson();
+  BuildInput.fromJson(super.json, {super.path}) : super.fromJson();
 
   BuildInput({
     required super.config,
@@ -80,12 +84,12 @@ class BuildInput extends HookInput {
 
   @override
   BuildConfig get config {
-    final jsonValue = json.map$('config');
-    return BuildConfig.fromJson(jsonValue);
+    final jsonValue = _reader.map$('config');
+    return BuildConfig.fromJson(jsonValue, path: [...path, 'config']);
   }
 
   Map<String, Map<String, Object?>>? get dependencyMetadata =>
-      json.optionalMap<Map<String, Object?>>('dependency_metadata');
+      _reader.optionalMap<Map<String, Object?>>('dependency_metadata');
 
   set _dependencyMetadata(Map<String, Map<String, Object?>>? value) {
     json.setOrRemove('dependency_metadata', value);
@@ -96,7 +100,7 @@ class BuildInput extends HookInput {
 }
 
 class BuildOutput extends HookOutput {
-  BuildOutput.fromJson(super.json) : super.fromJson();
+  BuildOutput.fromJson(super.json, {super.path}) : super.fromJson();
 
   BuildOutput({
     super.assets,
@@ -123,17 +127,22 @@ class BuildOutput extends HookOutput {
   }
 
   Map<String, List<Asset>>? get assetsForLinking {
-    final map_ = json.optionalMap('assetsForLinking');
-    if (map_ == null) {
+    final jsonValue = _reader.optionalMap('assetsForLinking');
+    if (jsonValue == null) {
       return null;
     }
-    return {
-      for (final MapEntry(:key, :value) in map_.entries)
-        key: [
-          for (final item in value as List<Object?>)
-            Asset.fromJson(item as Map<String, Object?>),
-        ],
-    };
+    final result = <String, List<Asset>>{};
+    for (final MapEntry(:key, :value) in jsonValue.entries) {
+      var index = 0;
+      result[key] = [
+        for (final item in value as List<Object?>)
+          Asset.fromJson(
+            item as Map<String, Object?>,
+            path: [...path, key, index++],
+          ),
+      ];
+    }
+    return result;
   }
 
   set assetsForLinking(Map<String, List<Asset>>? value) {
@@ -148,7 +157,7 @@ class BuildOutput extends HookOutput {
     json.sortOnKey();
   }
 
-  Map<String, Object?>? get metadata => json.optionalMap('metadata');
+  Map<String, Object?>? get metadata => _reader.optionalMap('metadata');
 
   set metadata(Map<String, Object?>? value) {
     json.setOrRemove('metadata', value);
@@ -162,14 +171,18 @@ class BuildOutput extends HookOutput {
 class Config {
   final Map<String, Object?> json;
 
-  Config.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
 
-  Config({required List<String> buildAssetTypes}) : json = {} {
+  Config.fromJson(this.json, {this.path = const []});
+
+  Config({required List<String> buildAssetTypes}) : json = {}, path = const [] {
     this.buildAssetTypes = buildAssetTypes;
     json.sortOnKey();
   }
 
-  List<String> get buildAssetTypes => json.stringList('build_asset_types');
+  List<String> get buildAssetTypes => _reader.stringList('build_asset_types');
 
   set buildAssetTypes(List<String> value) {
     json['build_asset_types'] = value;
@@ -183,7 +196,11 @@ class Config {
 class HookInput {
   final Map<String, Object?> json;
 
-  HookInput.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  HookInput.fromJson(this.json, {this.path = const []});
 
   HookInput({
     required Config config,
@@ -193,7 +210,8 @@ class HookInput {
     required String packageName,
     required Uri packageRoot,
     required String version,
-  }) : json = {} {
+  }) : json = {},
+       path = const [] {
     this.config = config;
     this.outDir = outDir;
     this.outDirShared = outDirShared;
@@ -205,8 +223,8 @@ class HookInput {
   }
 
   Config get config {
-    final jsonValue = json.map$('config');
-    return Config.fromJson(jsonValue);
+    final jsonValue = _reader.map$('config');
+    return Config.fromJson(jsonValue, path: [...path, 'config']);
   }
 
   set config(Config value) {
@@ -214,42 +232,42 @@ class HookInput {
     json.sortOnKey();
   }
 
-  Uri get outDir => json.path('out_dir');
+  Uri get outDir => _reader.path$('out_dir');
 
   set outDir(Uri value) {
     json['out_dir'] = value.toFilePath();
     json.sortOnKey();
   }
 
-  Uri get outDirShared => json.path('out_dir_shared');
+  Uri get outDirShared => _reader.path$('out_dir_shared');
 
   set outDirShared(Uri value) {
     json['out_dir_shared'] = value.toFilePath();
     json.sortOnKey();
   }
 
-  Uri? get outFile => json.optionalPath('out_file');
+  Uri? get outFile => _reader.optionalPath('out_file');
 
   set outFile(Uri? value) {
     json.setOrRemove('out_file', value?.toFilePath());
     json.sortOnKey();
   }
 
-  String get packageName => json.get<String>('package_name');
+  String get packageName => _reader.get<String>('package_name');
 
   set packageName(String value) {
     json.setOrRemove('package_name', value);
     json.sortOnKey();
   }
 
-  Uri get packageRoot => json.path('package_root');
+  Uri get packageRoot => _reader.path$('package_root');
 
   set packageRoot(Uri value) {
     json['package_root'] = value.toFilePath();
     json.sortOnKey();
   }
 
-  String get version => json.get<String>('version');
+  String get version => _reader.get<String>('version');
 
   set version(String value) {
     json.setOrRemove('version', value);
@@ -263,14 +281,19 @@ class HookInput {
 class HookOutput {
   final Map<String, Object?> json;
 
-  HookOutput.fromJson(this.json);
+  final List<Object> path;
+
+  JsonReader get _reader => JsonReader(json, path);
+
+  HookOutput.fromJson(this.json, {this.path = const []});
 
   HookOutput({
     List<Asset>? assets,
     List<Uri>? dependencies,
     required String timestamp,
     required String version,
-  }) : json = {} {
+  }) : json = {},
+       path = const [] {
     this.assets = assets;
     this.dependencies = dependencies;
     this.timestamp = timestamp;
@@ -278,10 +301,16 @@ class HookOutput {
     json.sortOnKey();
   }
 
-  List<Asset>? get assets => json.optionalListParsed(
-    'assets',
-    (e) => Asset.fromJson(e as Map<String, Object?>),
-  );
+  List<Asset>? get assets {
+    var index = 0;
+    return _reader.optionalListParsed(
+      'assets',
+      (e) => Asset.fromJson(
+        e as Map<String, Object?>,
+        path: [...path, 'assets', index++],
+      ),
+    );
+  }
 
   set assets(List<Asset>? value) {
     if (value == null) {
@@ -292,21 +321,21 @@ class HookOutput {
     json.sortOnKey();
   }
 
-  List<Uri>? get dependencies => json.optionalPathList('dependencies');
+  List<Uri>? get dependencies => _reader.optionalPathList('dependencies');
 
   set dependencies(List<Uri>? value) {
     json.setOrRemove('dependencies', value?.toJson());
     json.sortOnKey();
   }
 
-  String get timestamp => json.get<String>('timestamp');
+  String get timestamp => _reader.get<String>('timestamp');
 
   set timestamp(String value) {
     json.setOrRemove('timestamp', value);
     json.sortOnKey();
   }
 
-  String get version => json.get<String>('version');
+  String get version => _reader.get<String>('version');
 
   set version(String value) {
     json.setOrRemove('version', value);
@@ -318,7 +347,7 @@ class HookOutput {
 }
 
 class LinkInput extends HookInput {
-  LinkInput.fromJson(super.json) : super.fromJson();
+  LinkInput.fromJson(super.json, {super.path}) : super.fromJson();
 
   LinkInput({
     List<Asset>? assets,
@@ -344,10 +373,16 @@ class LinkInput extends HookInput {
     json.sortOnKey();
   }
 
-  List<Asset>? get assets => json.optionalListParsed(
-    'assets',
-    (e) => Asset.fromJson(e as Map<String, Object?>),
-  );
+  List<Asset>? get assets {
+    var index = 0;
+    return _reader.optionalListParsed(
+      'assets',
+      (e) => Asset.fromJson(
+        e as Map<String, Object?>,
+        path: [...path, 'assets', index++],
+      ),
+    );
+  }
 
   set _assets(List<Asset>? value) {
     if (value == null) {
@@ -357,7 +392,7 @@ class LinkInput extends HookInput {
     }
   }
 
-  Uri? get resourceIdentifiers => json.optionalPath('resource_identifiers');
+  Uri? get resourceIdentifiers => _reader.optionalPath('resource_identifiers');
 
   set _resourceIdentifiers(Uri? value) {
     json.setOrRemove('resource_identifiers', value?.toFilePath());
@@ -368,7 +403,7 @@ class LinkInput extends HookInput {
 }
 
 class LinkOutput extends HookOutput {
-  LinkOutput.fromJson(super.json) : super.fromJson();
+  LinkOutput.fromJson(super.json, {super.path}) : super.fromJson();
 
   LinkOutput({
     super.assets,
@@ -381,17 +416,27 @@ class LinkOutput extends HookOutput {
   String toString() => 'LinkOutput($json)';
 }
 
-extension on Map<String, Object?> {
+class JsonReader {
+  /// The JSON Object this reader is reading.
+  final Map<String, Object?> json;
+
+  /// The path traversed by readers of the surrounding JSON.
+  ///
+  /// Contains [String] property keys and [int] indices.
+  ///
+  /// This is used to give more precise error messages.
+  final List<Object> path;
+
+  JsonReader(this.json, this.path);
+
   T get<T extends Object?>(String key) {
-    final value = this[key];
+    final value = json[key];
     if (value is T) return value;
+    final pathString = _jsonPathToString([key]);
     if (value == null) {
-      throw FormatException('No value was provided for required key: $key');
+      throw FormatException("No value was provided for '$pathString'.");
     }
-    throw FormatException(
-      'Unexpected value \'$value\' for key \'.$key\'. '
-      'Expected a $T.',
-    );
+    throwFormatException(value, T, [key]);
   }
 
   List<T> list<T extends Object?>(String key) =>
@@ -404,14 +449,13 @@ extension on Map<String, Object?> {
       };
 
   /// [List.cast] but with [FormatException]s.
-  static List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+  List<T> _castList<T extends Object?>(List<Object?> list, String key) {
+    var index = 0;
     for (final value in list) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$list\' (${list.runtimeType}) for key \'.$key\'. '
-          'Expected a ${List<T>}.',
-        );
+        throwFormatException(value, T, [key, index]);
       }
+      index++;
     }
     return list.cast();
   }
@@ -435,16 +479,13 @@ extension on Map<String, Object?> {
       };
 
   /// [Map.cast] but with [FormatException]s.
-  static Map<String, T> _castMap<T extends Object?>(
+  Map<String, T> _castMap<T extends Object?>(
     Map<String, Object?> map_,
-    String key,
+    String parentKey,
   ) {
-    for (final value in map_.values) {
+    for (final MapEntry(:key, :value) in map_.entries) {
       if (value is! T) {
-        throw FormatException(
-          'Unexpected value \'$map_\' (${map_.runtimeType}) for key \'.$key\'.'
-          'Expected a ${Map<String, T>}.',
-        );
+        throwFormatException(value, T, [parentKey, key]);
       }
     }
     return map_.cast();
@@ -454,7 +495,7 @@ extension on Map<String, Object?> {
 
   List<String> stringList(String key) => list<String>(key);
 
-  Uri path(String key) => _fileSystemPathToUri(get<String>(key));
+  Uri path$(String key) => _fileSystemPathToUri(get<String>(key));
 
   Uri? optionalPath(String key) {
     final value = get<String?>(key);
@@ -477,6 +518,23 @@ extension on Map<String, Object?> {
     return Uri.file(path);
   }
 
+  String _jsonPathToString(List<Object> pathEnding) =>
+      [...path, ...pathEnding].join('.');
+
+  Never throwFormatException(
+    Object? value,
+    Type expectedType,
+    List<Object> pathExtension,
+  ) {
+    final pathString = _jsonPathToString(pathExtension);
+    throw FormatException(
+      "Unexpected value '$value' (${value.runtimeType}) for '$pathString'. "
+      'Expected a $expectedType.',
+    );
+  }
+}
+
+extension on Map<String, Object?> {
   void setOrRemove(String key, Object? value) {
     if (value == null) {
       remove(key);
diff --git a/pkgs/native_assets_cli/test/build_config_test.dart b/pkgs/native_assets_cli/test/build_input_test.dart
similarity index 66%
rename from pkgs/native_assets_cli/test/build_config_test.dart
rename to pkgs/native_assets_cli/test/build_input_test.dart
index 47e421f42..8e94fe3c2 100644
--- a/pkgs/native_assets_cli/test/build_config_test.dart
+++ b/pkgs/native_assets_cli/test/build_input_test.dart
@@ -11,6 +11,8 @@ import 'package:native_assets_cli/native_assets_cli_builder.dart';
 import 'package:native_assets_cli/src/config.dart' show latestVersion;
 import 'package:test/test.dart';
 
+import 'helpers.dart';
+
 void main() async {
   late Uri outFile;
   late Uri outDirUri;
@@ -18,6 +20,7 @@ void main() async {
   late String packageName;
   late Uri packageRootUri;
   late Map<String, Metadata> metadata;
+  late Map<String, Object?> inputJson;
 
   setUp(() async {
     final tempUri = Directory.systemTemp.uri;
@@ -33,24 +36,8 @@ void main() async {
       }),
       'foo': const Metadata({'key': 321}),
     };
-  });
 
-  test('BuildInputBuilder->JSON->BuildInput', () {
-    final inputBuilder =
-        BuildInputBuilder()
-          ..setupShared(
-            packageName: packageName,
-            packageRoot: packageRootUri,
-            outputFile: outFile,
-            outputDirectory: outDirUri,
-            outputDirectoryShared: outputDirectoryShared,
-          )
-          ..config.setupShared(buildAssetTypes: ['my-asset-type'])
-          ..config.setupBuild(linkingEnabled: false)
-          ..setupBuildInput(metadata: metadata);
-    final input = BuildInput(inputBuilder.json);
-
-    final expectedInputJson = {
+    inputJson = {
       'config': {
         'build_asset_types': ['my-asset-type'],
         'linking_enabled': false,
@@ -69,9 +56,25 @@ void main() async {
       'package_root': packageRootUri.toFilePath(),
       'version': latestVersion.toString(),
     };
+  });
 
-    expect(input.json, expectedInputJson);
-    expect(json.decode(input.toString()), expectedInputJson);
+  test('BuildInputBuilder->JSON->BuildInput', () {
+    final inputBuilder =
+        BuildInputBuilder()
+          ..setupShared(
+            packageName: packageName,
+            packageRoot: packageRootUri,
+            outputFile: outFile,
+            outputDirectory: outDirUri,
+            outputDirectoryShared: outputDirectoryShared,
+          )
+          ..config.setupShared(buildAssetTypes: ['my-asset-type'])
+          ..config.setupBuild(linkingEnabled: false)
+          ..setupBuildInput(metadata: metadata);
+    final input = BuildInput(inputBuilder.json);
+
+    expect(input.json, inputJson);
+    expect(json.decode(input.toString()), inputJson);
 
     expect(input.outputDirectory, outDirUri);
     expect(input.outputDirectoryShared, outputDirectoryShared);
@@ -87,21 +90,8 @@ void main() async {
   group('BuildInput format issues', () {
     for (final version in ['9001.0.0', '0.0.1']) {
       test('BuildInput version $version', () {
-        final outDir = outDirUri;
-        final input = {
-          'config': {
-            'build_asset_types': ['my-asset-type'],
-            'linking_enabled': false,
-            'target_os': 'linux',
-            'link_mode_preference': 'prefer-static',
-          },
-          'out_dir': outDir.toFilePath(),
-          'out_dir_shared': outputDirectoryShared.toFilePath(),
-          'out_file': outFile.toFilePath(),
-          'package_root': packageRootUri.toFilePath(),
-          'version': version,
-          'package_name': packageName,
-        };
+        final input = inputJson;
+        input['version'] = version;
         expect(
           () => BuildInput(input),
           throwsA(
@@ -116,59 +106,55 @@ void main() async {
       });
     }
 
-    test('BuildInput FormatExceptions', () {
+    test('BuildInput FormatException out_dir', () {
+      final input = inputJson;
+      input.remove('out_dir');
       expect(
-        () => BuildInput({}),
+        () => BuildInput(input),
         throwsA(
           predicate(
             (e) =>
                 e is FormatException &&
-                e.message.contains('No value was provided for required key: '),
+                e.message.contains("No value was provided for 'out_dir'."),
           ),
         ),
       );
+    });
+
+    test('BuildInput FormatException dependency_metadata', () {
+      final input = inputJson;
+      input['dependency_metadata'] = {
+        'bar': {'key': 'value'},
+        'foo': <int>[],
+      };
       expect(
-        () => BuildInput({
-          'version': latestVersion.toString(),
-          'package_name': packageName,
-          'package_root': packageRootUri.toFilePath(),
-          'target_os': 'android',
-        }),
+        () => BuildInput(input),
         throwsA(
           predicate(
             (e) =>
                 e is FormatException &&
-                e.message.contains(
-                  'No value was provided for required key: out_dir',
-                ),
+                e.message.contains('Unexpected value') &&
+                e.message.contains('dependency_metadata.foo') &&
+                e.message.contains('Expected a Map<String, Object?>'),
           ),
         ),
       );
+    });
+
+    test('BuildInput FormatException config.build_asset_types', () {
+      final input = inputJson;
+      traverseJson<Map<String, Object?>>(input, [
+        'config',
+      ]).remove('build_asset_types');
       expect(
-        () => BuildInput({
-          'config': {
-            'build_asset_types': ['my-asset-type'],
-            'linking_enabled': false,
-          },
-          'version': latestVersion.toString(),
-          'out_dir': outDirUri.toFilePath(),
-          'out_dir_shared': outputDirectoryShared.toFilePath(),
-          'out_file': outFile.toFilePath(),
-          'package_name': packageName,
-          'package_root': packageRootUri.toFilePath(),
-          'target_os': 'android',
-          'dependency_metadata': {
-            'bar': {'key': 'value'},
-            'foo': <int>[],
-          },
-        }),
+        () => BuildInput(input).config.buildAssetTypes,
         throwsA(
           predicate(
             (e) =>
                 e is FormatException &&
-                e.message.contains('Unexpected value') &&
                 e.message.contains(
-                  'Expected a Map<String, Map<String, Object?>>',
+                  'No value was provided for '
+                  "'config.build_asset_types'.",
                 ),
           ),
         ),
diff --git a/pkgs/native_assets_cli/test/code_assets/config_test.dart b/pkgs/native_assets_cli/test/code_assets/config_test.dart
index e47803d7c..c94ff007c 100644
--- a/pkgs/native_assets_cli/test/code_assets/config_test.dart
+++ b/pkgs/native_assets_cli/test/code_assets/config_test.dart
@@ -5,9 +5,10 @@
 import 'dart:io';
 
 import 'package:native_assets_cli/code_assets_builder.dart';
-import 'package:native_assets_cli/src/config.dart' show latestVersion;
 import 'package:test/test.dart';
 
+import '../helpers.dart';
+
 void main() async {
   late Uri outDirUri;
   late Uri outputDirectoryShared;
@@ -49,7 +50,7 @@ void main() async {
   // check the nested key.
   Map<String, Object> inputJson({
     String hookType = 'build',
-    bool includeDeprecated = true,
+    bool includeDeprecated = false,
     OS targetOS = OS.android,
   }) => {
     if (hookType == 'link')
@@ -148,15 +149,13 @@ void main() async {
             ),
           );
     final input = BuildInput(inputBuilder.json);
-    expect(input.json, inputJson());
+    expect(input.json, inputJson(includeDeprecated: true));
     expectCorrectCodeConfig(input.config.code);
   });
 
   test('BuildInput from json without deprecated keys', () {
     for (final targetOS in [OS.android, OS.iOS, OS.macOS]) {
-      final input = BuildInput(
-        inputJson(includeDeprecated: false, targetOS: targetOS),
-      );
+      final input = BuildInput(inputJson(targetOS: targetOS));
       expect(input.packageName, packageName);
       expect(input.packageRoot, packageRootUri);
       expect(input.outputDirectory, outDirUri);
@@ -197,7 +196,7 @@ void main() async {
             ),
           );
     final input = LinkInput(inputBuilder.json);
-    expect(input.json, inputJson(hookType: 'link'));
+    expect(input.json, inputJson(hookType: 'link', includeDeprecated: true));
     expectCorrectCodeConfig(input.config.code);
     expect(input.assets.encodedAssets, assets);
   });
@@ -221,23 +220,12 @@ void main() async {
   });
 
   test('BuildInput.config.code: invalid architecture', () {
-    final input = {
-      'config': {
-        'code': {
-          'link_mode_preference': 'prefer-static',
-          'android': {'target_ndk_api': 30},
-          'target_architecture': 'invalid_architecture',
-          'target_os': 'android',
-        },
-        'linking_enabled': false,
-      },
-      'out_dir': outDirUri.toFilePath(),
-      'out_dir_shared': outputDirectoryShared.toFilePath(),
-      'out_file': outFile.toFilePath(),
-      'package_name': packageName,
-      'package_root': packageRootUri.toFilePath(),
-      'version': latestVersion.toString(),
-    };
+    final input = inputJson();
+    traverseJson<Map<String, Object?>>(input, [
+          'config',
+          'code',
+        ])['target_architecture'] =
+        'invalid_architecture';
     expect(
       () => BuildInput(input).config.code.targetArchitecture,
       throwsFormatException,
@@ -245,22 +233,67 @@ void main() async {
   });
 
   test('LinkInput.config.code: invalid os', () {
-    final input = {
-      'config': {
-        'code': {
-          'link_mode_preference': 'prefer-static',
-          'android': {'target_ndk_api': 30},
-          'target_architecture': 'x64',
-          'target_os': 'invalid_os',
-        },
-      },
-      'out_dir': outDirUri.toFilePath(),
-      'out_dir_shared': outputDirectoryShared.toFilePath(),
-      'out_file': outFile.toFilePath(),
-      'package_name': packageName,
-      'package_root': packageRootUri.toFilePath(),
-      'version': latestVersion.toString(),
-    };
+    final input = inputJson(hookType: 'link');
+    traverseJson<Map<String, Object?>>(input, ['config', 'code'])['target_os'] =
+        'invalid_os';
     expect(() => LinkInput(input).config.code.targetOS, throwsFormatException);
   });
+
+  test('LinkInput.config.code.target_os invalid type', () {
+    final input = inputJson(hookType: 'link');
+    traverseJson<Map<String, Object?>>(input, ['config', 'code'])['target_os'] =
+        123;
+    expect(
+      () => LinkInput(input).config.code.targetOS,
+      throwsA(
+        predicate(
+          (e) =>
+              e is FormatException &&
+              e.message.contains(
+                "Unexpected value '123' (int) for 'config.code.target_os'. "
+                'Expected a String.',
+              ),
+        ),
+      ),
+    );
+  });
+
+  test('LinkInput.config.code.link_mode_preference missing', () {
+    final input = inputJson(hookType: 'link');
+    traverseJson<Map<String, Object?>>(input, [
+      'config',
+      'code',
+    ]).remove('link_mode_preference');
+    expect(
+      () => LinkInput(input).config.code.linkModePreference,
+      throwsA(
+        predicate(
+          (e) =>
+              e is FormatException &&
+              e.message.contains(
+                "No value was provided for 'config.code.link_mode_preference'.",
+              ),
+        ),
+      ),
+    );
+  });
+  test('LinkInput.assets.0.link_mode missing', () {
+    final input = inputJson(hookType: 'link');
+    traverseJson<Map<String, Object?>>(input, [
+      'assets',
+      0,
+    ]).remove('link_mode');
+    expect(
+      () => LinkInput(input).assets.code.first.linkMode,
+      throwsA(
+        predicate(
+          (e) =>
+              e is FormatException &&
+              e.message.contains(
+                "No value was provided for 'assets.0.link_mode'.",
+              ),
+        ),
+      ),
+    );
+  });
 }
diff --git a/pkgs/native_assets_cli/test/code_assets/validation_test.dart b/pkgs/native_assets_cli/test/code_assets/validation_test.dart
index 4873fead9..415cc5b2b 100644
--- a/pkgs/native_assets_cli/test/code_assets/validation_test.dart
+++ b/pkgs/native_assets_cli/test/code_assets/validation_test.dart
@@ -8,6 +8,8 @@ import 'package:native_assets_cli/code_assets_builder.dart';
 import 'package:native_assets_cli/src/code_assets/validation.dart';
 import 'package:test/test.dart';
 
+import '../helpers.dart';
+
 void main() {
   late Uri tempUri;
   late Uri outDirUri;
@@ -326,20 +328,3 @@ void main() {
     });
   });
 }
-
-T traverseJson<T extends Object?>(Object json, List<Object> path) {
-  while (path.isNotEmpty) {
-    final key = path.removeAt(0);
-    switch (key) {
-      case final int i:
-        json = (json as List)[i] as Object;
-        break;
-      case final String s:
-        json = (json as Map)[s] as Object;
-        break;
-      default:
-        throw UnsupportedError(key.toString());
-    }
-  }
-  return json as T;
-}
diff --git a/pkgs/native_assets_cli/test/helpers.dart b/pkgs/native_assets_cli/test/helpers.dart
index 2a3815d78..bcc86c776 100644
--- a/pkgs/native_assets_cli/test/helpers.dart
+++ b/pkgs/native_assets_cli/test/helpers.dart
@@ -202,3 +202,20 @@ Logger _createTestLogger({
 final dartExecutable = File(Platform.resolvedExecutable).uri;
 
 int defaultMacOSVersion = 13;
+
+T traverseJson<T extends Object?>(Object json, List<Object> path) {
+  while (path.isNotEmpty) {
+    final key = path.removeAt(0);
+    switch (key) {
+      case final int i:
+        json = (json as List)[i] as Object;
+        break;
+      case final String s:
+        json = (json as Map)[s] as Object;
+        break;
+      default:
+        throw UnsupportedError(key.toString());
+    }
+  }
+  return json as T;
+}
diff --git a/pkgs/native_assets_cli/test/link_config_test.dart b/pkgs/native_assets_cli/test/link_input_test.dart
similarity index 68%
rename from pkgs/native_assets_cli/test/link_config_test.dart
rename to pkgs/native_assets_cli/test/link_input_test.dart
index 32785e9a6..e3f720488 100644
--- a/pkgs/native_assets_cli/test/link_config_test.dart
+++ b/pkgs/native_assets_cli/test/link_input_test.dart
@@ -16,6 +16,7 @@ void main() async {
   late String packageName;
   late Uri packageRootUri;
   late List<EncodedAsset> assets;
+  late Map<String, Object?> inputJson;
 
   setUp(() async {
     final tempUri = Directory.systemTemp.uri;
@@ -28,6 +29,19 @@ void main() async {
       for (int i = 0; i < 3; i++)
         EncodedAsset('my-asset-type', {'a-$i': 'v-$i'}),
     ];
+
+    inputJson = {
+      'assets': [for (final asset in assets) asset.toJson()],
+      'config': {
+        'build_asset_types': ['asset-type-1', 'asset-type-2'],
+      },
+      'out_dir_shared': outputDirectoryShared.toFilePath(),
+      'out_dir': outDirUri.toFilePath(),
+      'out_file': outFile.toFilePath(),
+      'package_name': packageName,
+      'package_root': packageRootUri.toFilePath(),
+      'version': latestVersion.toString(),
+    };
   });
 
   test('LinkInputBuilder->JSON->LinkInput', () {
@@ -46,20 +60,8 @@ void main() async {
           ..setupLink(assets: assets, recordedUsesFile: null);
     final input = LinkInput(inputBuilder.json);
 
-    final expectedInputJson = {
-      'assets': [for (final asset in assets) asset.toJson()],
-      'config': {
-        'build_asset_types': ['asset-type-1', 'asset-type-2'],
-      },
-      'out_dir_shared': outputDirectoryShared.toFilePath(),
-      'out_dir': outDirUri.toFilePath(),
-      'out_file': outFile.toFilePath(),
-      'package_name': packageName,
-      'package_root': packageRootUri.toFilePath(),
-      'version': latestVersion.toString(),
-    };
-    expect(input.json, expectedInputJson);
-    expect(json.decode(input.toString()), expectedInputJson);
+    expect(input.json, inputJson);
+    expect(json.decode(input.toString()), inputJson);
 
     expect(input.outputDirectory, outDirUri);
     expect(input.outputDirectoryShared, outputDirectoryShared);
@@ -73,15 +75,8 @@ void main() async {
   group('LinkInput FormatExceptions', () {
     for (final version in ['9001.0.0', '0.0.1']) {
       test('LinkInput version $version', () {
-        final outDir = outDirUri;
-        final input = {
-          'out_dir': outDir.toFilePath(),
-          'out_dir_shared': outputDirectoryShared.toFilePath(),
-          'out_file': outFile.toFilePath(),
-          'package_root': packageRootUri.toFilePath(),
-          'version': version,
-          'package_name': packageName,
-        };
+        final input = inputJson;
+        input['version'] = version;
         expect(
           () => LinkInput(input),
           throwsA(
@@ -95,50 +90,33 @@ void main() async {
         );
       });
     }
-    test('LinkInput FormatExceptions', () {
-      expect(
-        () => LinkInput({}),
-        throwsA(
-          predicate(
-            (e) =>
-                e is FormatException &&
-                e.message.contains('No value was provided for required key: '),
-          ),
-        ),
-      );
+
+    test('LinkInput FormatException out_dir', () {
+      final input = inputJson;
+      input.remove('out_dir');
       expect(
-        () => LinkInput({
-          'version': latestVersion.toString(),
-          'package_name': packageName,
-          'package_root': packageRootUri.toFilePath(),
-          'assets': <String>[],
-        }),
+        () => LinkInput(input),
         throwsA(
           predicate(
             (e) =>
                 e is FormatException &&
-                e.message.contains(
-                  'No value was provided for required key: out_dir',
-                ),
+                e.message.contains("No value was provided for 'out_dir'."),
           ),
         ),
       );
+    });
+
+    test('LinkInput FormatExceptions', () {
+      final input = inputJson;
+      input['assets'] = 'astring';
       expect(
-        () => LinkInput({
-          'version': latestVersion.toString(),
-          'out_dir': outDirUri.toFilePath(),
-          'out_dir_shared': outputDirectoryShared.toFilePath(),
-          'out_file': outFile.toFilePath(),
-          'package_name': packageName,
-          'package_root': packageRootUri.toFilePath(),
-          'assets': 'astring',
-        }),
+        () => LinkInput(input),
         throwsA(
           predicate(
             (e) =>
                 e is FormatException &&
                 e.message.contains(
-                  "Unexpected value 'astring' for key '.assets'. "
+                  "Unexpected value 'astring' (String) for 'assets'. "
                   'Expected a List<Object?>?.',
                 ),
           ),