Add another `None` check.

src/models.py

@@ -122,7 +122,7 @@ class PlayLog(db.Model):
 
         if track:
             # Station fallback may not provide a duration. Take this one, it's better than nothing.
-            if track.track_duration == 0:
+            if track.track_duration == 0 or not track.track_duration:
                 return track
 
             # Preferably only get playlogs which are known for still being on air