fix: Add exception logging to Stream.trigger (#6902)

Author: Azaya89

holoviews/streams.py

@@ -242,8 +242,23 @@ def trigger(cls, streams):
         )
 
         with triggering_streams(streams):
+            errors = []
             for subscriber in subscribers:
-                subscriber(**dict(union))
+                try:
+                    subscriber(**dict(union))
+                except Exception as e:
+                    errors.append(e)
+
+            # Re-raise a single error directly to preserve its original exception
+            # type e.g. AbbreviatedException.
+            # NOTE: With Python 3.11 we can use an ExceptionGroup.
+            if len(errors) == 1:
+                raise errors[0]
+            elif errors:
+                raise RuntimeError(
+                    f"{len(errors)} stream subscribers raised an exception. "
+                    "All subscribers were invoked regardless."
+                ) from Exception(*errors)
 
         for stream in streams:
             with util.disable_constant(stream):

holoviews/tests/test_streams.py

@@ -160,6 +160,26 @@ def test_explicit_parameter(self):
         assert self.ExplicitTest.param["test"].default == 42
         assert self.ExplicitTest.param["test"].doc == "Test docstring"
 
+    def test_subscriber_error_logging_isolation(self):
+        xy = self.XY()
+        calls = []
+
+        def bad_subscriber(**kw):
+            calls.append("bad")
+            raise RuntimeError("bad subscriber")
+
+        def good_subscriber(**kw):
+            calls.append("good")
+
+        xy.add_subscriber(bad_subscriber)
+        xy.add_subscriber(good_subscriber)
+
+        with pytest.raises(RuntimeError, match="bad subscriber"):
+            Stream.trigger([xy])
+
+        assert len(calls) == 2
+        assert calls == ["bad", "good"]
+
 
 class _Subscriber:
     def __init__(self, cb=None):