When a file was already in cache, add_from_reader() would return
immediately after reading only 1024 bytes to compute the pk. This
closed the flac_stream and pcm_tx, causing the pump to terminate
normally. However, the dispatcher treated track_tx.send() failure
as a fatal error, even though the pump had completed successfully.
Changes:
- In phase 3 post-prebuffer, when track_tx.send() fails, wait for
pump to complete and check its result
- If pump returned Ok(), drain remaining segments until TrackBoundary
- If pump returned Err(), propagate the error
- This allows graceful handling of cache hits while preserving error
detection for genuine pump failures
Fixes the "Pump task died" error when relaunching play_and_cache
with existing cached files.
483ec26dfe