FIX: Always return 2-tuple from _skip_to_earliest_waiting_event

skipci

octue/cloud/events/handler.py

@@ -222,7 +222,7 @@ def _skip_to_earliest_waiting_event(self):
         try:
             event, attributes = self.waiting_events.pop(self._earliest_waiting_event_number)
         except KeyError:
-            return
+            return None, None
 
         number_of_missing_events = self._earliest_waiting_event_number - self._previous_event_number - 1