fix: Address code review issues in JS dependency manager

This commit addresses all code review feedback:

1. Improved instance variable initialization pattern
   - Changed from @added_dependencies_to_package_json ||= false
   - To: @added_dependencies_to_package_json = false unless defined?(@added_dependencies_to_package_json)
   - Added clear documentation explaining the initialization is done by the module

2. Made error messages more specific
   - All raise statements now include which packages failed
   - Added context that failure indicates shakapacker may not be properly installed
   - Error messages now help users understand what went wrong

3. Documented add_js_dependency method usage
   - Added YARD-style documentation
   - Clarified it's used for single package with version (react-on-rails@VERSION)
   - Explained add_js_dependencies_batch is for batch operations
   - Both methods now have clear @param and @return documentation

4. Fixed TypeScript dependency installation inconsistency
   - Removed manual instance variable setting
   - Now uses consistent pattern with shared module approach
   - Raises specific error instead of just warning if installation fails
   - Matches the error handling pattern of other dependency methods

5. Fixed RuboCop violations
   - Removed redundant begin block in install_js_dependencies
   - All files now pass bundle exec rubocop with zero offenses

All tests pass successfully (6 examples, 0 failures).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

lib/generators/react_on_rails/install_generator.rb

@@ -374,26 +374,14 @@ def install_typescript_dependencies
           @babel/preset-typescript
         ]
 
-        # Try using GeneratorHelper first (package manager agnostic)
-        if add_npm_dependencies(typescript_packages, dev: true)
-          @added_dependencies_to_package_json = true
-          return
-        end
-
-        # Fallback to npm if GeneratorHelper fails
-        success = system("npm", "install", "--save-dev", *typescript_packages)
-        if success
-          @ran_direct_installs = true
-          return
+        # Use the shared dependency management approach via GeneratorHelper
+        unless add_npm_dependencies(typescript_packages, dev: true)
+          # This should not happen since package_json is always available via shakapacker
+          raise "Failed to add TypeScript dependencies (#{typescript_packages.join(', ')}) via package_json gem. " \
+                "This indicates shakapacker dependency may not be properly installed."
         end
 
-        warning = <<~MSG.strip
-          ⚠️  Failed to install TypeScript dependencies automatically.
-
-          Please run manually:
-              npm install --save-dev #{typescript_packages.join(' ')}
-        MSG
-        GeneratorMessages.add_warning(warning)
+        @added_dependencies_to_package_json = true
       end
 
       def create_css_module_types

lib/generators/react_on_rails/js_dependency_manager.rb

@@ -52,7 +52,9 @@ module JsDependencyManager
       private
 
       def setup_js_dependencies
-        @added_dependencies_to_package_json ||= false
+        # Initialize instance variable if not already defined by including class
+        # This ensures safe operation when the module is first included
+        @added_dependencies_to_package_json = false unless defined?(@added_dependencies_to_package_json)
         add_js_dependencies
         install_js_dependencies
       end
@@ -73,7 +75,8 @@ def add_react_on_rails_package
           @added_dependencies_to_package_json = true
         else
           # This should not happen since package_json is always available via shakapacker
-          raise "Failed to add react-on-rails package via package_json gem"
+          raise "Failed to add react-on-rails package via package_json gem. " \
+                "This indicates shakapacker dependency may not be properly installed."
         end
       end
 
@@ -84,7 +87,8 @@ def add_react_dependencies
           @added_dependencies_to_package_json = true
         else
           # This should not happen since package_json is always available via shakapacker
-          raise "Failed to add React dependencies via package_json gem"
+          raise "Failed to add React dependencies (#{REACT_DEPENDENCIES.join(', ')}) via package_json gem. " \
+                "This indicates shakapacker dependency may not be properly installed."
         end
       end
 
@@ -95,7 +99,8 @@ def add_css_dependencies
           @added_dependencies_to_package_json = true
         else
           # This should not happen since package_json is always available via shakapacker
-          raise "Failed to add CSS dependencies via package_json gem"
+          raise "Failed to add CSS dependencies (#{CSS_DEPENDENCIES.join(', ')}) via package_json gem. " \
+                "This indicates shakapacker dependency may not be properly installed."
         end
       end
 
@@ -106,11 +111,20 @@ def add_dev_dependencies
           @added_dependencies_to_package_json = true
         else
           # This should not happen since package_json is always available via shakapacker
-          raise "Failed to add development dependencies via package_json gem"
+          raise "Failed to add development dependencies (#{DEV_DEPENDENCIES.join(', ')}) via package_json gem. " \
+                "This indicates shakapacker dependency may not be properly installed."
         end
       end
 
       # Add a single dependency using package_json gem
+      #
+      # This method is used internally for adding the react-on-rails package
+      # with version-specific handling (react-on-rails@VERSION).
+      # For batch operations, use add_js_dependencies_batch instead.
+      #
+      # @param package [String] Package specifier (e.g., "[email protected]")
+      # @param dev [Boolean] Whether to add as dev dependency
+      # @return [Boolean] true if successful, false otherwise
       def add_js_dependency(package, dev: false)
         pj = package_json
         return false unless pj
@@ -131,28 +145,33 @@ def add_js_dependency(package, dev: false)
       end
 
       # Add multiple dependencies at once using package_json gem
+      #
+      # This method delegates to GeneratorHelper's add_npm_dependencies for
+      # better package manager abstraction and batch processing efficiency.
+      #
+      # @param packages [Array<String>] Package names to add
+      # @param dev [Boolean] Whether to add as dev dependencies
+      # @return [Boolean] true if successful, false otherwise
       def add_js_dependencies_batch(packages, dev: false)
         # Use the add_npm_dependencies helper from GeneratorHelper
         add_npm_dependencies(packages, dev: dev)
       end
 
       def install_js_dependencies
         # Use package_json gem's install method (always available via shakapacker)
-        begin
-          package_json.manager.install
-          true
-        rescue StandardError => e
-          GeneratorMessages.add_warning(<<~MSG.strip)
-            ⚠️  JavaScript dependencies installation failed: #{e.message}
-
-            This could be due to network issues or package manager problems.
-            You can install dependencies manually later by running:
-            • npm install (if using npm)
-            • yarn install (if using yarn)
-            • pnpm install (if using pnpm)
-          MSG
-          false
-        end
+        package_json.manager.install
+        true
+      rescue StandardError => e
+        GeneratorMessages.add_warning(<<~MSG.strip)
+          ⚠️  JavaScript dependencies installation failed: #{e.message}
+
+          This could be due to network issues or package manager problems.
+          You can install dependencies manually later by running:
+          • npm install (if using npm)
+          • yarn install (if using yarn)
+          • pnpm install (if using pnpm)
+        MSG
+        false
       end
 
       # No longer needed since package_json gem handles package manager detection