Merge branch '12-handle-playback-error-handling' into 'develop'

Resolve "Crashes in handle_playback cancel loop"

Closes #12

See merge request ekzyis/musicube!13

src/bot.py

@@ -9,7 +9,7 @@ from dotenv import load_dotenv
 import youtube_dl
 
 from error import ErrorHandler
-from message import NowPlayingMessage, QueuedMessage
+from message import NowPlayingMessage, QueuedMessage, ErrorMessage
 
 load_dotenv()
 
@@ -54,22 +54,40 @@ class Music(commands.Cog):
     # pylint: disable=no-member
     self._handle_playback.cancel()
 
+  def _next(self):
+    """Trigger playback of next song."""
+    self._queue.task_done()
+    if self._queue_lock.locked():
+      self._queue_lock.release()
+
   @tasks.loop()
   async def _handle_playback(self):
     while True:
+      try:
         await self._queue_lock.acquire()
         ctx, song = await self._queue.get()
+        if ctx.voice_client is None:
+          # Bot is no longer in a voice channel.
+          # This could be the case because a stop command was issued.
+          # We will skip this (and possibly all remaining songs) in the queue
+          self._next()
+          continue
         audio = discord.FFmpegPCMAudio(song.audio_url, **self._ffmpeg_options)
 
         def after(err):
           if err:
             print(f"Player error: {err}")
-        self._queue.task_done()
-        self._queue_lock.release()
+          self._next()
         ctx.voice_client.play(audio, after=after)
-
         embed = NowPlayingMessage(title=song.title, url=song.webpage_url)
         await ctx.send(embed=embed)
+      # pylint: disable=broad-except
+      except Exception as err:
+        print(f"Error during playback: {err}")
+        if ctx:
+          embed = ErrorMessage(str(err))
+          await ctx.send(embed=embed)
+        self._next()
 
   @_handle_playback.before_loop
   async def before_handle_playback(self):