Refactor and improve audio system:

- Fix potential uninitialized variable issue in `oslDecodeWav` by initializing `streambuffer` to NULL and checking before freeing it.
- Add null checks and improve error handling in `oslAudioCallback_PlaySound_WAV`, `oslAudioCallback_AudioCallback_WAV`, `oslAudioCallback_ReactiveSound_WAV`, and `oslAudioCallback_StandBy_WAV`.
- Improve `oslAudioCallback_DeleteSound_WAV` with added null safety and proper memory management.
- Refactor `oslLoadSoundFileWAV` for better error handling, memory safety, and readability, including consolidated error handling and memory deallocation in case of failure.