Default proxy config error management needs a review

[Zicchio]

The current proxy configuration is designed so that when un uncatght exception is thrown at some endpoint (response endpoint or request endpoint), then a generic error page is returned.

This page is intended to be read by a user but it not correct for http requests that starts from a wallet, such as an authorization response in direct_post mode. In those cases, we should always provide error responses compliant with openid4vp and the italian profile for openid4vp+sd-jwt

[peppelinux]

this seems related to iam-proxy-italia

at the same time this issue aims to clarify that for the wallet flow we need pure json responses according to openid4vp and not an http page

we have already improved the error handling using only json responses, this issue will be resolved once the review will enrich this thread with the evidences about the missing error handling