fix: AttributeErrors from event handler move (#1946)

Fix event issues from #1907

Author: NeloBlivion

discord/cog.py

@@ -735,7 +735,7 @@ def _remove_module_references(self, name: str) -> None:
                 self.remove_application_command(cmd)
 
         # remove all the listeners from the module
-        for event_list in self.extra_events.copy().values():
+        for event_list in self._event_handlers.copy().values():
             remove = [
                 index
                 for index, event in enumerate(event_list)

discord/ext/commands/bot.py

@@ -159,7 +159,7 @@ async def on_command_error(
 
         This only fires if you do not specify any listeners for command error.
         """
-        if self.extra_events.get("on_command_error", None):
+        if self._event_handlers.get("on_command_error", None):
             return
 
         command = context.command