Middleware errors when a vetting type hint is not present

[phavekes]

This issue is imported from pivotal - Originaly created at Feb 9, 2023 by Michiel Kodde

Background
The following error is raised in MW via SelfService interaction when the vetting hint is not configured.

{"channel":"app","level":"ERROR","message":"Vetting type hint for institution \'institution-b.nl\' was not found","context":{"exception":{"class":"Symfony\\Component\\HttpKernel\\Exception\\NotFoundHttpException","message":"Vetting type hint for institution \'institution-b.nl\' was not found","code":0,"file":"/opt/openconext/OpenConext-middleware-5.0.7/src/Surfnet/StepupMiddleware/ApiBundle/Controller/VettingTypeHintController.php:67","previous":{"class":"Surfnet\\StepupMiddleware\\ApiBundle\\Exception\\NotFoundException","message":"Vetting type hint not found for institution institution-b.nl","code":0,"file":"/opt/openconext/OpenConext-middleware-5.0.7/src/Surfnet/StepupMiddleware/CommandHandlingBundle/Identity/Service/VettingTypeHintService.php:85"}}},"extra":{"art":"89116","server":"middleware.test2.surfconext.nl","application":"middleware","request_id":"8f718c32e1a45f8a2c739ef18b3e07a9"}}

Steps to reproduce:

Initially the issue arose when an identity vetted a SF token and was presented with the vetting type screen. This would cause the MW to trigger an error that was not dealt with correctly in the SA.

As of february 13th, both Pieter and Michiel are unable to reproduce the issue.

Middleware client bundle interprets this as an errorous situation and in turn throws a NotFoundException which SelfService catches and interprets as: no vetting type hint was set..

An error is written to the Middleware logs though. And that might be somewhat excessive.

*Possible solutions: *

1. Middleware should not throw a not found exception, but return an empty result (null). This would entail a change to middleware client bundle and self-service.
2. The log level in middleware could be lowered somehow. That would still change the current behavior.