title: KeyError on Discord.Py
body: <pre><code>@client.command(description="Pauses the current playing track. Can be resumed with `!resume`.", 
  brief="Pauses current track.",aliases=['PAUSE'])
  async def pause(ctx):
      guild_id = ctx.message.guild.id
      players[guild_id].pause()
  
  @client.command(description="Resumes the current playing track. Can only be used if current track has 
  been paused.",
      brief="Resumes current track.",
      aliases=['RESUME','continue','CONTINUE'])
  async def resume(ctx):
      guild_id = ctx.message.guild.id
      players[guild_id].resume()
  
  @client.command(description="Stops the current playing track.",
       brief="Stops current track.",
       aliases=['STOP'])
  async def stop(ctx):
      guild_id = ctx.message.guild.id
      players[guild_id].stop()
  </code></pre>
  
  <p><strong>When i try to use the pause, stop and resume command it gives me the KeyError. The whole code that triggers that error is up there. And the error lokks like this:</strong></p>
  
  <p>Ignoring exception in command stop:
  Traceback (most recent call last):
    File "C:\Users\emirs\PycharmProjects\discordmasterbot\venv\lib\site-packages\discord\ext\commands\core.py", line 83, in wrapped
      ret = await coro(*args, **kwargs)
    File "C:/Users/emirs/PycharmProjects/discordmasterbot/MASTERBOT.py", line 163, in stop
      players[guild_id].stop()
  KeyError: 708748879079932016</p>
  
  <p><strong>And there is an another type of that error:</strong></p>
  
  <p>Traceback (most recent call last):
    File "C:\Users\emirs\PycharmProjects\discordmasterbot\venv\lib\site-packages\discord\ext\commands\bot.py", line 892, in invoke
      await ctx.command.invoke(ctx)
    File "C:\Users\emirs\PycharmProjects\discordmasterbot\venv\lib\site-packages\discord\ext\commands\core.py", line 797, in invoke
      await injected(*ctx.args, **ctx.kwargs)
    File "C:\Users\emirs\PycharmProjects\discordmasterbot\venv\lib\site-packages\discord\ext\commands\core.py", line 92, in wrapped
      raise CommandInvokeError(exc) from exc
  discord.ext.commands.errors.CommandInvokeError: Command raised an exception: KeyError: 708748879079932016</p>