A local call waiting for a slot is reached by a stop, a delete or a cancel and ends without running; what a call emits after its flow was stopped is dropped as its result is; a node run by hand whose flow is stopped or deleted tells its caller but publishes no node_error; cancelling a node also ends its calls on workers

backend/fluksio/flow/controller.py

@@ -2113,6 +2113,8 @@ class FlowController:
         node = self.get_node(node_id)
         if node is None:
             raise KeyError(node_id)
+        pipeline = self.pipeline
+        ended = pipeline.ended(node.flow) if pipeline is not None else 0
         try:
             if node.requires and values:
                 node.trigger(values, durable=False)
@@ -2121,9 +2123,14 @@ class FlowController:
         except EngineHeld:
             raise
         except Exception as exc:
-            if self.pipeline is None:
+            if pipeline is None:
                 raise
-            return self.pipeline.publish_error(node, exc)
+            if pipeline.ended(node.flow) != ended:
+                # Its flow was stopped or deleted while it ran, most likely
+                # ending the call. The person who clicked is told, alert rules
+                # are not, as for a cascade.
+                return f"{type(exc).__name__}: {exc}"
+            return pipeline.publish_error(node, exc)
         return ""
 
     def _publish(self, event: dict[str, Any]) -> None: