diff --git a/src/compiler/builder.ts b/src/compiler/builder.ts
index 62dd670fbc5f6..06615b3a97f51 100644
--- a/src/compiler/builder.ts
+++ b/src/compiler/builder.ts
@@ -78,7 +78,8 @@ namespace ts {
         if (useOldState) {
             // Verify the sanity of old state
             if (!oldState!.currentChangedFilePath) {
-                Debug.assert(!oldState!.affectedFiles && (!oldState!.currentAffectedFilesSignatures || !oldState!.currentAffectedFilesSignatures!.size), "Cannot reuse if only few affected files of currentChangedFile were iterated");
+                const affectedSignatures = oldState!.currentAffectedFilesSignatures;
+                Debug.assert(!oldState!.affectedFiles && (!affectedSignatures || !affectedSignatures.size), "Cannot reuse if only few affected files of currentChangedFile were iterated");
             }
             if (canCopySemanticDiagnostics) {
                 Debug.assert(!forEachKey(oldState!.changedFilesSet, path => oldState!.semanticDiagnosticsPerFile!.has(path)), "Semantic diagnostics shouldnt be available for changed files");
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index f976f77ea985a..53e455050142b 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -7774,17 +7774,18 @@ namespace ts {
                     const libReferenceDirectives = context.libReferenceDirectives;
                     forEach(toArray(entryOrList), (arg: PragmaPseudoMap["reference"]) => {
                         // TODO: GH#18217
+                        const { types, lib, path } = arg!.arguments;
                         if (arg!.arguments["no-default-lib"]) {
                             context.hasNoDefaultLib = true;
                         }
-                        else if (arg!.arguments.types) {
-                            typeReferenceDirectives.push({ pos: arg!.arguments.types!.pos, end: arg!.arguments.types!.end, fileName: arg!.arguments.types!.value });
+                        else if (types) {
+                            typeReferenceDirectives.push({ pos: types.pos, end: types.end, fileName: types.value });
                         }
-                        else if (arg!.arguments.lib) {
-                            libReferenceDirectives.push({ pos: arg!.arguments.lib!.pos, end: arg!.arguments.lib!.end, fileName: arg!.arguments.lib!.value });
+                        else if (lib) {
+                            libReferenceDirectives.push({ pos: lib.pos, end: lib.end, fileName: lib.value });
                         }
-                        else if (arg!.arguments.path) {
-                            referencedFiles.push({ pos: arg!.arguments.path!.pos, end: arg!.arguments.path!.end, fileName: arg!.arguments.path!.value });
+                        else if (path) {
+                            referencedFiles.push({ pos: path.pos, end: path.end, fileName: path.value });
                         }
                         else {
                             reportDiagnostic(arg!.range.pos, arg!.range.end - arg!.range.pos, Diagnostics.Invalid_reference_directive_syntax);
diff --git a/src/harness/compiler.ts b/src/harness/compiler.ts
index 532a2d655789a..70bda90ef32db 100644
--- a/src/harness/compiler.ts
+++ b/src/harness/compiler.ts
@@ -183,8 +183,9 @@ namespace compiler {
         }
 
         public getSourceMapRecord(): string | undefined {
-            if (this.result!.sourceMaps && this.result!.sourceMaps!.length > 0) {
-                return Harness.SourceMapRecorder.getSourceMapRecord(this.result!.sourceMaps!, this.program!, Array.from(this.js.values()).filter(d => !ts.fileExtensionIs(d.file, ts.Extension.Json)), Array.from(this.dts.values()));
+            const maps = this.result!.sourceMaps;
+            if (maps && maps.length > 0) {
+                return Harness.SourceMapRecorder.getSourceMapRecord(maps, this.program!, Array.from(this.js.values()).filter(d => !ts.fileExtensionIs(d.file, ts.Extension.Json)), Array.from(this.dts.values()));
             }
         }