unwrap panic in audio_playback_device_spec

[fschulze]

Great wrapper!

I get a panic due to a failing unwrap in audio_playback_device_spec on macOS when trying to get the spec of the first device which is an external HDMI display (I hope the backtrace is useful, as it isn't a native one):

Backtrace (most recent call last):
  File "~/.cargo/registry/src/index.crates.io-6f17d22bba15001f/sdl2-0.36.0/src/sdl2/audio.rs:202", in sdl2::audio::<impl sdl2::sdl::AudioSubsystem>::audio_playback_device_spec
    Ok(AudioSpec::convert_from_ll(spec))
  File "~/.cargo/registry/src/index.crates.io-6f17d22bba15001f/sdl2-0.36.0/src/sdl2/audio.rs:721", in sdl2::audio::AudioSpec::convert_from_ll
    format: AudioFormat::from_ll(spec.format).unwrap(),
  File "rust:library/core/src/option.rs:935", in core::option::Option<T>::unwrap
  File "rust:library/core/src/panicking.rs:127", in core::panicking::panic

I would expect audio_playback_device_spec to return an error instead.

It looks like audio_playback_device_spec is new in 0.36, which isn't mentioned in the changelog afaict (and the tag is missing in the repository).

[Cobrand]

This is coming from AudioFormat::from_ll(spec.format).unwrap(), which means that spec.format is not recognized.

Otherwise yes, we could avoid this panic by changing AudioSpec::convert_from_ll to return Result<AudioSpec, ()> instead of AudioSpec and panicking on unrecognized spec format.

[fschulze]

I should add that this happens during enumeration of the audio devices. So it is likely that the format isn't known at that point.