fix(slack_alerting.py): support region based outage alerting

litellm/main.py

@@ -420,6 +420,8 @@ def mock_completion(
                 api_key="mock-key",
             )
         if isinstance(mock_response, Exception):
+            if isinstance(mock_response, openai.APIError):
+                raise mock_response
             raise litellm.APIError(
                 status_code=500,  # type: ignore
                 message=str(mock_response),
@@ -463,7 +465,9 @@ def mock_completion(
 
         return model_response
 
-    except:
+    except Exception as e:
+        if isinstance(e, openai.APIError):
+            raise e
         traceback.print_exc()
         raise Exception("Mock completion response failed")