fix 0 is not a valid EventType

Author: eternal-sorrow

i3ipc/connection.py

@@ -425,7 +425,6 @@ def _on(self, event: Union[Event, str], handler: Handler):
             self._pubsub.subscribe(event, handler)
             return
 
-        event_type = EventType(0)
         if base_event == 'workspace':
             event_type = EventType.WORKSPACE
         elif base_event == 'output':
@@ -444,8 +443,7 @@ def _on(self, event: Union[Event, str], handler: Handler):
             event_type = EventType.TICK
         elif base_event == 'input':
             event_type = EventType.INPUT
-
-        if not event_type:
+        else:
             raise Exception('event not implemented')
 
         self.subscriptions |= event_type.value