[commands] Make the CommandError required argument optional again.

discord/ext/commands/errors.py

@@ -39,10 +39,13 @@ class CommandError(DiscordException):
     in a special way as they are caught and passed into a special event
     from :class:`Bot`\, :func:`on_command_error`.
     """
-    def __init__(self, message):
-        # clean-up @everyone and @here mentions
-        m = message.replace('@everyone', '@\u200beveryone').replace('@here', '@\u200bhere')
-        super().__init__(m)
+    def __init__(self, message=None, *args):
+        if message is not None:
+            # clean-up @everyone and @here mentions
+            m = message.replace('@everyone', '@\u200beveryone').replace('@here', '@\u200bhere')
+            super().__init__(m, *args)
+        else:
+            super().__init__(*args)
 
 class CommandNotFound(CommandError):
     """Exception raised when a command is attempted to be invoked