Nick Bowler [Fri, 1 May 2020 23:55:41 +0000 (19:55 -0400)]
karaoke-flagger: Don't break on stanadlone recordings.
When standalone recordings are loaded into Picard, the "track" metadata
processor is called with a "track" parameter that is not actually a
track at all, but a recording.
We actually only care about the recording so assume it is the recording
if it lacks the "recording" key.