Exception when show that is currently being tracked is removed from the list

[FichteFoll]

Steps to reproduce

1. Add a show to the list without sending it to remote.
2. Start playing an episode of this show (using the mpris tracker here, but should happen with any).
3. Force-retrieve the list from remote, essentially undoing the addition of the show earlier.
4. Close the player.

Result

Traceback (most recent call last):
  File "/home/fichte/code/trackma/trackma/engine.py", line 418, in get_show_info
    return showdict[showid]
KeyError: 98595

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/fichte/code/trackma/trackma/tracker/mpris.py", line 225, in observe_async
    await asyncio.gather(*tasks)
  File "/home/fichte/code/trackma/trackma/tracker/mpris.py", line 103, in properties_watcher
    handle_properties_changed(tracker, msg)
  File "/home/fichte/code/trackma/trackma/tracker/mpris.py", line 113, in handle_properties_changed
    tracker.on_playback_status_change(sender, playback_status)
  File "/home/fichte/code/trackma/trackma/tracker/mpris.py", line 273, in on_playback_status_change
    self._handle_player_update(player)
  File "/home/fichte/code/trackma/trackma/tracker/mpris.py", line 287, in _handle_player_update
    self._handle_player_stopped()
  File "/home/fichte/code/trackma/trackma/tracker/mpris.py", line 343, in _handle_player_stopped
    self.update_show_if_needed(state, show_tuple)
  File "/home/fichte/code/trackma/trackma/tracker/tracker.py", line 220, in update_show_if_needed
    self._update_state(state)
  File "/home/fichte/code/trackma/trackma/tracker/tracker.py", line 163, in _update_state
    self._emit_signal(
  File "/home/fichte/code/trackma/trackma/tracker/tracker.py", line 106, in _emit_signal
    self.signals[signal](*args)
  File "/home/fichte/code/trackma/trackma/engine.py", line 147, in _tracker_playing
    show = self.get_show_info(showid)
  File "/home/fichte/code/trackma/trackma/engine.py", line 420, in get_show_info
    raise utils.EngineError("Show not found.")
trackma.utils.EngineError: Show not found.