Whether the playing track has a playlist location.
Row in that playlist; null when there is no location.
Playlist index; null when there is no location.
GUID of that playlist, as playlistGuid takes it; null when there is no location.
Always true here; a failed call resolves with ApiFailure instead.
OptionaltrackThe track at that location; only with includeTrackInfo, and only when the row still exists.
Successful response from
playback.getCurrentTrackIndex.