Fix KeyError('event_name') in DataBlock.process_events for control-only events

pydatalab/src/pydatalab/blocks/base.py

@@ -262,8 +262,10 @@ def process_events(self, events: list[dict] | dict):
             events = [events]
 
         for event in events:
-            # Match the event to any registered by the block
-            if (event_name := event.pop("event_name")) in self.event_names:
+            # Match the event to any registered by the block. Events without an
+            # `event_name` (e.g. a bare `{"trigger_async": True}` control flag sent
+            # by the in-situ blocks) are not registered events, so skip them.
+            if (event_name := event.pop("event_name", None)) in self.event_names:
                 # Bind the method to the instance before calling
                 bound_method = self.__class__.events_by_name[event_name].__get__(
                     self, self.__class__

pydatalab/tests/test_base_block.py

@@ -11,6 +11,16 @@ def test_base_block():
     assert block.data["kwargs"]["d"] == "string"
 
 
+def test_process_events_ignores_events_without_event_name():
+    """Regression test: in-situ blocks (XRD/NMR/UVVis) trigger async processing by
+    posting a bare `{"trigger_async": True}` event with no `event_name` key, which
+    previously raised `KeyError: 'event_name'` in `process_events`.
+    """
+    block = DataBlock(item_id="test-id")
+    block.process_events({"trigger_async": True})
+    assert "errors" not in block.data
+
+
 def test_callback():
     callback = generate_js_callback_single_float_parameter(
         "set_wavelength", "wavelength", block_id="test", throttled=False