diff --git a/endpoints/helpers.py b/endpoints/helpers.py
index c9628b2..579fcc2 100644
--- a/endpoints/helpers.py
+++ b/endpoints/helpers.py
@@ -4,6 +4,7 @@
 from middlewares.discord_middleware import DiscordMiddleware
 from middlewares.default_middleware import DefaultMiddleware
 
+
 def apply_middleware(r: Request, settings: Mapping) -> Optional[Response]:
     """
     Applies middleware based on the settings provided.
@@ -34,6 +35,7 @@ def apply_middleware(r: Request, settings: Mapping) -> Optional[Response]:
 
     return None
 
+
 def validate_api_key(r: Request, settings: Mapping) -> Optional[Response]:
     """
     Validates the API key based on the location specified in the settings.
@@ -54,7 +56,7 @@ def validate_api_key(r: Request, settings: Mapping) -> Optional[Response]:
         if request_api_key != expected_api_key:
             return Response(json.dumps({"error": "Invalid API key"}),
                             status=403, content_type="application/json")
-    
+
     elif api_key_location == "token_query_param":
         request_api_key = r.args.get("difyToken")
         if request_api_key != expected_api_key:
@@ -63,7 +65,13 @@ def validate_api_key(r: Request, settings: Mapping) -> Optional[Response]:
 
     return None
 
-EndpointRoute = Literal["/workflow/<app_id>", "/chatflow/<app_id>", "/single-workflow", "/single-chatflow"]
+
+EndpointRoute = Literal[
+    "/workflow/<app_id>",
+    "/chatflow/<app_id>",
+    "/single-workflow",
+    "/single-chatflow"
+]
 
 def determine_route(path: str) -> Optional[EndpointRoute]:
     """
@@ -83,4 +91,4 @@ def determine_route(path: str) -> Optional[EndpointRoute]:
         return "/single-workflow"
     elif path.startswith("/single-chatflow"):
         return "/single-chatflow"
-    return None
\ No newline at end of file
+    return None
diff --git a/endpoints/invoke_endpoint.py b/endpoints/invoke_endpoint.py
index e6b174c..5b2cb27 100644
--- a/endpoints/invoke_endpoint.py
+++ b/endpoints/invoke_endpoint.py
@@ -149,13 +149,13 @@ def _invoke(self, r: Request, values: Mapping, settings: Mapping) -> Response:
                 response = self._invoke_workflow(
                     static_app_id, inputs, settings.get('raw_data_output', False))
 
-            if not response:
-                return Response(json.dumps({"error": "Failed to get response"}), status=500, content_type="application/json")
             else:
                 # Return response
                 logger.debug("%s response: %s", route, response)
                 return Response(json.dumps(response), status=200, content_type="application/json")
 
+            if not response:
+                return Response(json.dumps({"error": "Failed to get response"}), status=500, content_type="application/json")
         except (json.JSONDecodeError, KeyError, TypeError) as e:
             logger.error("Error during request processing: %s", str(e))
             return Response(json.dumps({"error": str(e)}), status=500, content_type="application/json")