getTrackSources for undefined track

[danielr18]

https://github.com/benwiley4000/cassette/blob/da848c2d42c471343622d25262f6ef1cc23be63e/packages/core/src/PlayerContextProvider.js#L348

I think I found another case when this can happen, we discussed it on #318. If you have a playlist with 3 tracks, and activeIndex: 2, and the playlist is changed to only have one track, it would try to access the activeIndex of the new playlist, which would be undefined and throw an error.

[benwiley4000]

Good catch! Thank you.

Check out this part of static getDerivedStateFromProps:

    // the sources if we stay on the same track index
    const currentSources = getTrackSources(
      newPlaylist,
      prevState.activeTrackIndex
    );
    // non-comprehensive but probably accurate check
    if (prevSources[0].src === currentSources[0].src) {
      // our active track index already matches
      return baseNewState;
    }

I think we can wrap all of that in an if statement and if it's false then we automatically find a new activeTrackIndex afterward:

    if (newPlaylist[prevState.activeTrackIndex]) {
        // the sources if we stay on the same track index
        const currentSources = getTrackSources(
          newPlaylist,
          prevState.activeTrackIndex
        );
        // non-comprehensive but probably accurate check
        if (prevSources[0].src === currentSources[0].src) {
          // our active track index already matches
          return baseNewState;
        }
    }

I haven't tested this though so it's hard to be sure.

I will probably have time to deal with this sometime later this week, unless you want to submit a PR. 🙂

[danielr18]

I'll create the PR, and test it.