When utilizing the Forge impersonation feature, the current error message received is somewhat unclear:

PROXY_ERR: Forge platform failed to process runtime HTTP request - 401 - MISSING_OR_INELIGIBLE_USER

To improve debugging, it would be beneficial if the response could explicitly check for malformed user IDs. In such cases, returning a distinct error code (e.g., MALFORMED_USER_ID) or providing a clearer message would be helpful. This change would aid in quickly diagnosing issues related to user ID formatting errors.