Unhandled exception for "list <tag> title <something>"

[kingosticks]

We don't support the title tag in our filtering of list output. For example the command:

list artist title "something like avalanches"

does not complete properly and we get:

MpdSession-18 ERROR    2020-04-16 23:59:31,764 Unhandled exception in MpdSession (urn:uuid:9b7cefd5-7466-460c-a461-2950f2f0ea39):
Traceback (most recent call last):
  File "/home/nick/.virtualenvs/mopidy3/lib/python3.7/site-packages/pykka/_actor.py", line 193, in _actor_loop
    response = self._handle_receive(envelope.message)
  File "/home/nick/.virtualenvs/mopidy3/lib/python3.7/site-packages/pykka/_actor.py", line 307, in _handle_receive
    return self.on_receive(message)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/network.py", line 443, in on_receive
    self.on_line_received(line)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/session.py", line 32, in on_line_received
    response = self.dispatcher.handle_request(line)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 46, in handle_request
    return self._call_next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 69, in _call_next_filter
    return next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 77, in _catch_mpd_ack_errors_filter
    return self._call_next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 69, in _call_next_filter
    return next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 90, in _authenticate_filter
    return self._call_next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 69, in _call_next_filter
    return next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 106, in _command_list_filter
    response = self._call_next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 69, in _call_next_filter
    return next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 139, in _idle_filter
    response = self._call_next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 69, in _call_next_filter
    return next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 152, in _add_ok_filter
    response = self._call_next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 69, in _call_next_filter
    return next_filter(request, response, filter_chain)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 164, in _call_handler_filter
    response = self._format_response(self._call_handler(request))
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/dispatcher.py", line 178, in _call_handler
    return protocol.commands.call(tokens, context=self.context)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/protocol/__init__.py", line 212, in call
    return self.handlers[tokens[0]](context, *tokens[1:])
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/protocol/__init__.py", line 170, in validate
    return func(*args, **kwargs)
  File "/home/nick/Dev/mopidy-dev/mopidy-mpd/mopidy_mpd/protocol/music_db.py", line 292, in list_
    return [(name, value) for value in result.get()]
  File "/home/nick/.virtualenvs/mopidy3/lib/python3.7/site-packages/pykka/_threading.py", line 45, in get
    _compat.reraise(*self._data['exc_info'])
  File "/home/nick/.virtualenvs/mopidy3/lib/python3.7/site-packages/pykka/_compat/__init__.py", line 29, in reraise
    raise value
  File "/home/nick/.virtualenvs/mopidy3/lib/python3.7/site-packages/pykka/_actor.py", line 193, in _actor_loop
    response = self._handle_receive(envelope.message)
  File "/home/nick/.virtualenvs/mopidy3/lib/python3.7/site-packages/pykka/_actor.py", line 299, in _handle_receive`
    return callee(*message.args, **message.kwargs)
  File "/home/nick/Dev/mopidy-dev/mopidy/mopidy/core/library.py", line 137, in get_distinct
    query is None or validation.check_query(query)  # TODO: normalize?
  File "/home/nick/Dev/mopidy-dev/mopidy/mopidy/internal/validation.py", line 109, in check_query
    msg="Expected query field to be one of " "{choices}, not {arg!r}",
  File "/home/nick/Dev/mopidy-dev/mopidy/mopidy/internal/validation.py", line 62, in check_choice
    msg.format(arg=arg, choices=tuple(choices))
mopidy.exceptions.ValidationError: Expected query field to be one of ('performer', 'albumartist', 'album', 'artist', 'date', 'track_name', 'genre', 'composer', 'any', 'comment', 'musicbrainz_albumid', 'track_no', 'uri'), not 'track'

This is because we are using the _LIST_MAPPING instead of _SEARCH_MAPPING to transform the filter query keys into what Mopidy Core expects ('track' -> 'track_name').