fix: fixes error when no flutter binary was present and notifies user that we could not find the executable (#480)

Author: kaerumm

lua/flutter-tools/executable.lua

@@ -49,9 +49,10 @@ local function _flutter_sdk_dart_bin(flutter_sdk)
 end
 
 ---Get paths for flutter and dart based on the binary locations
----@return table<string, string>
+---@return table<string, string>?
 local function get_default_binaries()
   local flutter_bin = fn.resolve(fn.exepath("flutter"))
+  if #flutter_bin <= 0 then return nil end
   return {
     flutter_bin = flutter_bin,
     dart_bin = fn.resolve(fn.exepath("dart")),
@@ -66,7 +67,7 @@ function M.reset_paths() _paths = nil end
 
 ---Execute user's lookup command and pass it to the job callback
 ---@param lookup_cmd string
----@param callback fun(p: string, t: table<string, string>?)
+---@param callback fun(t?: table<string, string>?)
 ---@return table<string, string>?
 local function path_from_lookup_cmd(lookup_cmd, callback)
   local paths = {}
@@ -110,7 +111,7 @@ local function _flutter_bin_from_fvm()
 end
 
 ---Fetch the paths to the users binaries.
----@param callback fun(paths: table<string, string>)
+---@param callback fun(paths?: table<string, string>)
 ---@return nil
 function M.get(callback)
   if _paths then return callback(_paths) end
@@ -138,14 +139,17 @@ function M.get(callback)
 
   if config.flutter_lookup_cmd then
     return path_from_lookup_cmd(config.flutter_lookup_cmd, function(paths)
+      if not paths then return end
       _paths = paths
       _paths.dart_sdk = _dart_sdk_root(_paths)
       callback(_paths)
     end)
   end
 
-  if not _paths then
-    _paths = get_default_binaries()
+  local default_paths = get_default_binaries()
+
+  if not _paths and default_paths then
+    _paths = default_paths
     _paths.dart_sdk = _dart_sdk_root(_paths)
     if _paths.flutter_sdk then _paths.dart_bin = _flutter_sdk_dart_bin(_paths.flutter_sdk) end
   end

lua/flutter-tools/lsp/init.lua

@@ -1,6 +1,7 @@
 local lazy = require("flutter-tools.lazy")
 local utils = lazy.require("flutter-tools.utils") ---@module "flutter-tools.utils"
 local path = lazy.require("flutter-tools.utils.path") ---@module "flutter-tools.utils.path"
+local ui = lazy.require("flutter-tools.ui") ---@module "flutter-tools.ui"
 local color = lazy.require("flutter-tools.lsp.color") ---@module "flutter-tools.lsp.color"
 local lsp_utils = lazy.require("flutter-tools.lsp.utils") ---@module "flutter-tools.lsp.utils"
 
@@ -216,6 +217,14 @@ local function get_server_config(user_config, callback)
   local executable = require("flutter-tools.executable")
   --- TODO: if a user specifies a command we do not need to call executable.get
   executable.get(function(paths)
+    if not paths then
+      ui.notify(
+        "Flutter executable could not be found, please make sure that flutter_path is given"
+          .. " or flutter_lookup_cmd is given or fvm is setup or that the flutter binary is "
+          .. "in your path"
+      )
+      return
+    end
     local defaults = get_defaults({ flutter_sdk = paths.flutter_sdk })
     local root_path = paths.dart_sdk
     local debug_log = create_debug_log(user_config.debug)