- Introduced `WatcherCriticalError` enum to categorize critical errors from the file watcher.
- Added a `CriticalErrorHandler` callback type for custom error handling in the watcher thread.
- Updated `StdBackend` to include a receiver for critical errors, allowing for better error management and logging.
- Refactored the watcher thread to handle errors gracefully instead of terminating the process, improving overall stability.
