title: Discord.py: Purge command raising CommandError
body: <p>For whatever reason, 2 weeks later my completely untouched code for my purge command in my bot stopped working. Upon inspecting it, there seems to be absolutely nothing wrong with it.</p>
  <p>Here is what I have:</p>
  <pre><code>@commands.cooldown(1, 10, commands.BucketType.user)
  @commands.has_permissions(manage_messages=True)
  @commands.command(aliases=['Purge', 'delete', 'del', 'clear', 'clr'])
  async def purge(self, ctx, amount):
    limit = amount # amount you're deleting
    await ctx.channel.purge(limit=limit+1) # uses the argument for the amount to actually delete the messages
    await ctx.send(str(amount) + &quot; messages have been deleted.&quot;, delete_after=5.0) # sends how many messages were deleted
  </code></pre>