[Frontend] Standardize use of create_error_response (#32319)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/entrypoints/openai/api_server.py

@@ -368,14 +368,8 @@ async def create_completion(request: CompletionRequest, raw_request: Request):
 
     try:
         generator = await handler.create_completion(request, raw_request)
-    except OverflowError as e:
-        raise HTTPException(
-            status_code=HTTPStatus.BAD_REQUEST.value, detail=str(e)
-        ) from e
     except Exception as e:
-        raise HTTPException(
-            status_code=HTTPStatus.INTERNAL_SERVER_ERROR.value, detail=str(e)
-        ) from e
+        return handler.create_error_response(e)
 
     if isinstance(generator, ErrorResponse):
         return JSONResponse(