fix test

api/core/app/apps/advanced_chat/generate_task_pipeline.py

@@ -511,6 +511,7 @@ class AdvancedChatAppGenerateTaskPipeline:
                         workflow_execution=workflow_execution,
                     )
                     workflow_outputs = workflow_finish_resp.data.outputs
+                    if workflow_outputs:
                         filtered_outputs = {k: v for k, v in workflow_outputs.items() if k != "answer"}
                         self._task_state.metadata.outputs = filtered_outputs
                 yield workflow_finish_resp