[Bug]: When there is a server error from ISEN side, backend response with a 401 Unauthorized error code

[Sigeth]

Short description

Sometimes, ISEN login page will have a 500 Internal Server Error error when trying to log in. It appeared frequently recently, so we did not take this possibility into an account. So by now the API sends a 401 Unauthorized error because the ISEN server is not replying with a 200 status code.

Expected Behavior

When ISEN server is having a 500 Internal Server Error, the API should answer back with a 502 Bad Gateway status code.

Actual Behavior

When ISEN server is having a 500 Internal Server Error, the API answer 401 Unauthorized for the /token endpoint, 500 Internal Server Error for the others.

Steps to Reproduce the Problem

1. It seems to happen randomly, so wait ISEN server to send you a 500 Internal Server Error on the login page
2. Call the /token endpoint