[Audio] Remove players which no longer have a guild. (#2414)

Cleanup players when the bot has one for a guild it leaves.

Bumps Red-Lavalink to v0.2.2

redbot/cogs/audio/audio.py

@@ -2624,3 +2624,20 @@ class Audio(commands.Cog):
             self._cleaned_up = True
 
     __del__ = __unload
+
+    async def on_guild_remove(self, guild: discord.Guild):
+        """
+        This is to clean up players when
+        the bot either leaves or is removed from a guild
+        """
+        channels = {
+            x  # x is a voice_channel
+            for y in [g.voice_channels for g in self.bot.guilds]
+            for x in y  # y is a list of voice channels
+        }  # Yes, this is ugly. It's also the most performant and commented.
+
+        zombie_players = {p for p in lavalink.player_manager.players if p.channel not in channels}
+        # Do not unroll to combine with next line.
+        # Can result in iterator changing size during context switching.
+        for zombie in zombie_players:
+            await zombie.destroy()

setup.py

@@ -19,7 +19,7 @@ install_requires = [
     "pyyaml==3.13",
     "raven==6.10.0",
     "raven-aiohttp==0.7.0",
-    "red-lavalink==0.2.1",
+    "red-lavalink==0.2.2",
     "schema==0.6.8",
     "websockets==7.0",
     "yarl==1.3.0",