Authentication plugins - Whitelabel error page is shown when user does not exist

[davide-negretti]

Describe the bug When external authentication plugins (such as Shibboleth) are being used, a new ePerson is automatically created for each external account.

If the automatic creation is disabled, when an user logs in with an external provider then the "whitelabel error page" is shown. An error message should be shown instead.

To Reproduce

1. Set authentication-shibboleth.autoregister = false in authentication-shibboleth.cfg
2. Log in using an external account that doesn't have an associated ePerson

Expected behavior An error message should be shown informing the user that the account does not exist.

Documentation https://wiki.lyrasis.org/display/DSDOC7x/Authentication+Plugins#AuthenticationPlugins-ShibbolethAuthentication

[abollini]

@tdonohue we can start to work on that. Right now it is still unclear how to solve the issue so the estimation needs to be refined after further investigation but this would take more than 40 hours

[tdonohue]

@abollini : Came across this ticket previously assigned to 4Science. Should this remain assigned to you for 7.5, or should I unassign?