Fix backend mutex poisoned panic when stopping playback on OpenHome renderer
This commit addresses a panic that occurred when stopping playback on OpenHome renderers, which was caused by:
1. Mutex poisoning from unhandled panics in backend operations
2. A regression revealed after initial fixes, where inconsistent renderer state caused index out of bounds errors
Changes include:
- Added defensive error handling for mutex operations to prevent poisoning
- Implemented bounds-checking for current_index in sync_queue to handle inconsistent renderer states
- Removed redundant clear_queue calls that were causing additional failures
- Improved error tolerance in queue operations
The fix ensures that the backend mutex remains healthy and that inconsistent renderer states are handled gracefully rather than causing panics.
Eric Coissac
4f8f902f3f