fix: non-stream async invoke error.

src/pipeline/backend/backend.py

@@ -1,5 +1,5 @@
 from abc import ABC, abstractmethod
-from typing import Iterable, List
+from typing import Iterable, List, AsyncGenerator
 from emd.models import Model,Engine
 from typing import Iterable, List
 import os
@@ -200,7 +200,7 @@ def _transform_response(self, response):
 
     async def _atransform_response(self, response):
         # Transform response to sagemaker format
-        return self._aget_response(response)
+        return await self._aget_response(response)
 
     def _transform_streaming_response(self, response):
         # Transform response to sagemaker format
@@ -226,7 +226,7 @@ def _get_streaming_response(self, response) -> Iterable[List[str]]:
             logger.error(traceback.format_exc())
             yield self._format_streaming_response(json.dumps({"error": str(e)}))
 
-    async def _aget_streaming_response(self, response) -> Iterable[List[str]]:
+    async def _aget_streaming_response(self, response) -> AsyncGenerator[str, None]:
         try:
             async for chunk in response:
                 logger.info(f"chunk: {chunk}")