Enhanced Error Handling and Reporting

This PR enhances the error handling system to leverage Pest's superior error reporting capabilities while maintaining 100% backward compatibility with existing error interfaces.

✅ Implementation Complete

All items from the implementation plan have been completed:

• Analyze current error handling infrastructure
• Enhance convert_pest_error() in pest_bridge.rs with better error messages
• Add renamed_rules support for user-friendly error messages
• Add comprehensive error message tests
• Update report_errors() to optionally use enhanced Pest error information
• Maintain backward compatibility with existing error format
• Add position and span handling improvements
• Ensure WASM error serialization continues to work
• Test enhanced error messages with various error scenarios
• Verify language server integration remains functional
• Fix formatting issues with cargo fmt

🎯 Key Features

Enhanced Error Messages:

• User-friendly rule name mapping (e.g., "type assignment ('=' or '/=')" instead of "assign_t")
• Contextual hints based on error type
• Both short and extended error descriptions
• Accurate position and span tracking from Pest

Example Error Output:

Error at line 1, column 7
expected one of: type assignment ('=' or '/='), group assignment ('=' or '//='), generic parameters '<...>'

Details: At line 1, column 7: Expected type assignment ('=' or '/=') or group assignment ('=' or '//=') or generic parameters '<...>'.

Hint: Every rule needs an assignment operator ('=' for new rules, '/=' for type alternatives, or '//=' for group alternatives).

Enhanced Error Reporting:

• Updated report_errors() to display extended messages as diagnostic notes
• Maintained backward compatibility with existing error structure
• Works with both std and no_std configurations

WASM & Language Server Compatibility:

• ErrorMsg structure unchanged, ensuring WASM serialization works
• Extended error messages automatically available to language server via JSON serialization
• Verified serialization compatibility with existing tests

📊 Testing Results

• ✅ All 94 existing tests pass without modification
• ✅ 3 new tests added for enhanced error handling
• ✅ 1 new test for WASM serialization compatibility
• ✅ Parser comparison tests verify both parsers work correctly
• ✅ CLI validation confirmed working
• ✅ Formatting validated with cargo fmt

📝 Files Changed

Core Implementation:

• src/pest_bridge.rs: Enhanced convert_pest_error() with user-friendly messages
• src/parser.rs: Updated report_errors() to include extended messages as notes

Documentation:

• ENHANCED_ERROR_HANDLING.md: Comprehensive documentation of enhancements

Tests:

• Enhanced error handling tests in pest_bridge.rs
• WASM compatibility tests
• Error position tracking tests

🔄 Backward Compatibility

100% backward compatible:

• Existing error API unchanged
• Both parsers coexist peacefully
• Error format maintains same structure
• Display trait works as before
• WASM serialization unaffected
• Language server integration maintained

📈 Impact

Users now get significantly better error messages when using the Pest parser, making it easier to:

• Understand what went wrong
• Know what was expected
• Get hints on how to fix the issue
• Locate the exact position of errors

All while maintaining full compatibility with existing code and tools.

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