Loading info of playlist that contains uploaded songs fails

[whitelynx]

Ages ago I uploaded a bunch of tracks to what was then Google Play Music, and I've added them to playlists. When I browse my playlists at /muse/playlists, any playlist that has an uploaded track in it causes an error: it shows error reading playlists tracks in place of the number of tracks, and in the Mopidy log I see this traceback:

ERROR    2024-09-15 14:20:53,001 [22399:Core-10 (_actor_loop)] mopidy.core.playlists
  YTMusicBackend backend caused an exception.
Traceback (most recent call last):
  File "/usr/lib/python3.12/site-packages/mopidy/core/playlists.py", line 16, in _backend_error_handling
    yield
  File "/usr/lib/python3.12/site-packages/mopidy/core/playlists.py", line 197, in lookup
    playlist = backend.playlists.lookup(uri).get()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/pykka/_threading.py", line 45, in get
    _compat.reraise(*self._data['exc_info'])
  File "/usr/lib/python3.12/site-packages/pykka/_compat/__init__.py", line 29, in reraise
    raise value
  File "/usr/lib/python3.12/site-packages/pykka/_actor.py", line 193, in _actor_loop
    response = self._handle_receive(envelope.message)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/pykka/_actor.py", line 299, in _handle_receive
    return callee(*message.args, **message.kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/whitelynx/.local/lib/python3.12/site-packages/mopidy_ytmusic/playlist.py", line 36, in lookup
    tracks = self.backend.library.playlistToTracks(pls)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/whitelynx/.local/lib/python3.12/site-packages/mopidy_ytmusic/library.py", line 734, in playlistToTracks
    for a in track["artists"]:
             ~~~~~^^^^^^^^^^^
TypeError: 'NoneType' object is not iterable