Improve error handling for polling requests

[phavekes]

This issue is imported from pivotal - Originaly created at Sep 2, 2024 by Pieter van der Meulen

When the polling process fails on /authentication/status, the tiqr gssp returns a 'normal' 500 error response. While the client expects a response code.

This can be tested by sending a http request to the polling endpoint without an authentication being started. E.g.: curl -vvv https://tiqr.test2.surfconext.nl/authentication/status (without a session cookie this will surely fail)

The registration endpoint seems to work better: curl -vvv https://tiqr.test2.surfconext.nl/registration/status

Ensure that both status endpoints return the response the the web client expects.