Improve generator robustness and error handling

[justin808]

Summary

Improve the React on Rails install generator to be more robust with better error handling, validation, and package manager detection.

Background

PR #1896 contained several generator improvements that should be extracted and applied to current master.

Proposed Changes

1. Better Package Manager Detection

• Improve detection of npm vs yarn vs pnpm
• Handle edge cases where package manager isn't obvious
• Add validation that chosen package manager is actually available

2. Smarter Validation Skipping

• Skip version validation when react-on-rails package not yet installed
• Avoid false errors during initial installation
• Better error messages when validation does fail

3. Webpack Safety Checks

• Add checks before modifying webpack config
• Validate webpack config exists before attempting modifications
• Better error messages for webpack-related issues

4. Exact Version Specifications

• Use exact versions where needed to avoid dependency conflicts
• Document why certain packages need exact versions
• Provide clear upgrade path

5. Better Error Messages

• Provide actionable error messages
• Include suggestions for common issues
• Link to troubleshooting documentation

Files to Update

From PR #1896 as reference:

• lib/generators/react_on_rails/base_generator.rb
• lib/generators/react_on_rails/generator_helper.rb
• lib/generators/react_on_rails/install_generator.rb
• Generator templates in lib/generators/react_on_rails/templates/

Testing

• Test generator with npm, yarn, and pnpm
• Test in fresh Rails app
• Test in existing Rails app with react-on-rails
• Test error scenarios (missing dependencies, etc.)
• Verify all generator tests pass

Related

• Extracted from closed PR Upgrade Shakapacker to 9.3.0 #1896
• Complements smart error messages work in feat: Add smart error messages with actionable solutions #1834

Labels

enhancement, generator