Don't return Err result when ytdl produces a warning

[alecks]

Youtube-dl warning messages are written to stderr, causing songbird::ytdl to fail if one is produced. Since it's usually not fatal, I think that whether or not it should continue should be configurable.

[FelixMcFelix]

Thanks for raising this. Could you give some indication of the sort of warning/error that can pop up, or an example URL that's triggering failure?

Feel free to PR a new variant function which forcibly ignores errors, or that silences warning from youtube-dl. 😄

[alecks]

WARNING: Assuming --restrict-filenames since file system encoding cannot encode all characters. Set the LC_ALL environment variable to fix this. is pretty common, but it's possible (though not the best idea) to ignore it. Would it be okay to use tracing::warn for only warning messages in the original function?

[FelixMcFelix]

It should be, if you can find a way to reasonably/safely separate them out from any actual errors. Keep in mind that the track metadata is also output on stderr, and is siphoned off accordingly so that we can get away with fewer calls to youtube-dl (and fewer network requests).

Otherwise, please add --no-warnings to the default argument list.

[vilgotf]

I encountered this recently trying to play https://opus-codec.org/static/examples/samples/speech_orig.wav. yt-dl can download it, but songbird says that the warning "Falling back on generic information extractor" is an error thus failing to play