Bot errors if a channel is deleted

[mklarz]

Whenever the bot errors, it sends a message to the channel where the error happened. It will then remove the error message after x seconds.

If that channel gets deleted before the bot removes the error message the bot will error out. See log below.

bot_1    | _ClientEventTask exception was never retrieved
bot_1    | future: <ClientEventTask state=finished event=on_command_error coro=<function on_command_error at 0x7f872b8d5040> exception=TypeError('on_error() takes from 1 to 2 positional arguments but 3 were given')>
bot_1    | Traceback (most recent call last):
bot_1    |   File "/usr/local/lib/python3.9/site-packages/discord/client.py", line 343, in _run_event
bot_1    |     await coro(*args, **kwargs)
bot_1    |   File "/home/bot/bot.py", line 83, in on_command_error
bot_1    |     await msg.delete()
bot_1    |   File "/usr/local/lib/python3.9/site-packages/discord/message.py", line 1023, in delete
bot_1    |     await self._state.http.delete_message(self.channel.id, self.id)
bot_1    |   File "/usr/local/lib/python3.9/site-packages/discord/http.py", line 250, in request
bot_1    |     raise NotFound(r, data)
bot_1    | discord.errors.NotFound: 404 Not Found (error code: 10003): Unknown Channel
bot_1    |
bot_1    | During handling of the above exception, another exception occurred:
bot_1    |
bot_1    | Traceback (most recent call last):
bot_1    |   File "/usr/local/lib/python3.9/site-packages/discord/client.py", line 348, in _run_event
bot_1    |     await self.on_error(event_name, *args, **kwargs)
bot_1    | TypeError: on_error() takes from 1 to 2 positional arguments but 3 were given