error object:
invalid_request, missing_authentication,
invalid_authentication, not_found, and internal_error. Each endpoint lists
the HTTP statuses it can return.
API error responses also include X-Request-Id. If you send X-Request-Id with the request, SpaPortal echoes that value. Otherwise, SpaPortal generates a new one.
Handling errors
Read both the HTTP status and the JSON error code or message. Treat400, 401, and 404 as client-correctable errors. Retry only after you change the request.
Treat 500 as a temporary server error. Retry with backoff if the operation is safe to repeat.