Fix python operators: Also return a `DoraStatus` for non-input events

examples/python-operator-dataflow/object_detection.py

@@ -29,6 +29,7 @@ class Operator:
     ) -> DoraStatus:
         if dora_event["type"] == "INPUT":
             return self.on_input(dora_event, send_output)
+        return DoraStatus.CONTINUE
 
     def on_input(
         self,

examples/python-operator-dataflow/plot.py

@@ -33,6 +33,7 @@ class Operator:
     ) -> DoraStatus:
         if dora_event["type"] == "INPUT":
             return self.on_input(dora_event, send_output)
+        return DoraStatus.CONTINUE
 
     def on_input(
         self,