fix mismatched response format w/wo streaming guardrails (#568)

* fix mismatched response format w/wo streaming  guardrails

* fix & debug

* fix & rm debug

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

comps/cores/mega/orchestrator.py

@@ -72,6 +72,18 @@ async def schedule(self, initial_inputs: Dict, llm_parameters: LLMParams = LLMPa
                                         downstreams.remove(downstream)
                                 except re.error as e:
                                     print("Pattern invalid! Operation cancelled.")
+                            if len(downstreams) == 0 and llm_parameters.streaming:
+                                # turn the response to a StreamingResponse
+                                # to make the response uniform to UI
+                                def fake_stream(text):
+                                    yield "data: b'" + text + "'\n\n"
+                                    yield "data: [DONE]\n\n"
+
+                                self.dump_outputs(
+                                    node,
+                                    StreamingResponse(fake_stream(response["text"]), media_type="text/event-stream"),
+                                    result_dict,
+                                )
 
                     for d_node in downstreams:
                         if all(i in result_dict for i in runtime_graph.predecessors(d_node)):