test(llc): cover the last dispatch region's error guard

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: VelikovPetar

packages/stream_chat/test/src/client/channel/channel_event_handler_test.dart

@@ -888,6 +888,20 @@ void main() {
       verify(() => mutations.onMemberUpdated(member)).called(1);
     });
 
+    test('a throwing block 3 handler does not escape handleEvent', () {
+      when(
+        () => mutations.onUserStartWatching(any(), watcherCount: any(named: 'watcherCount')),
+      ).thenThrow(StateError('boom'));
+
+      handler.handleEvent(
+        Event(type: EventType.userWatchingStart, user: otherUser),
+      );
+
+      verify(
+        () => mutations.onUserStartWatching(otherUser, watcherCount: null),
+      ).called(1);
+    });
+
     test('a contained error is logged rather than swallowed', () {
       when(() => mutations.onMemberAdded(any())).thenThrow(StateError('boom'));