[DFC Orders] Improve OIDC Error Handling

[RaggedStaff]

Need to clean up OIDC processes to provide more meaningful error messging - currently just returning 500 errors.

Agreed we will never support linking multiple OFN accounts to the same OIDC account (needs error handling/meaningful message)

I (@RaggedStaff ) repeatedly get an error when attempting to link to my Keycloak realm admin account, other accounts work fine. Could this be due to duplication: I have a regular (non-producer/non-admin) OFN account with the same email, but not sure how that would impact ? Can we pass more detail back from the Keycloak response to better understand this errror ?

[RachL]

Agreed we will never support linking multiple OFN accounts to the same OIDC account (needs error handling/meaningful message)

I understand it like this:

• I have an account on staging FR
• I have another account on staging UK

I can't link both accounts to the same OIDC account. Is that correct?

If I change the email on OFN can I link all these accounts to the same OIDC account or is the problem elsewhere?

PS: just a note on issues writing @RaggedStaff - as you are doing all the testing for this piece of work I understand you and Maikel are creating issues quickly and it's clear for you both. But if one day Maikel is sick or the OFN testing team needs to step in, we would need issues according to template, or at least with clear acceptance tests criteria. Happy to discuss this further on future budgets.