v1.0.2: Add debug logging and enhance error handling for `bs-layer`

- Introduced `onDebug()` for detailed debug logging to assist development and troubleshooting.
- Expanded usage of `onError()` across various functions for consistent error reporting.
- Improved error messages and added robust error handling for critical operations.
- Updated functions like `open`, `close`, and `fetchContent` to include debug logs.
- Enhanced transparency in event and layer state management with logging at key points.