I code in AI2 MIT app inventor and its distributions. Some days before I coded an extension with which you can get directions from open route service directly from your app. So it is little restricted with its raw response until the response code is 200, So I never get raw error response.
However the request generated by the extension is in this format
https://api.openrouteservice.org/v2/directions/driving-car?api_key=user_api_key&start=longitude,latitude&end=longitude,latitude
However its open source you can check it out here: