[FIX] SAML login undefined error message

[galshiff]

Proposed changes

Return the SAML login error to the user instead of undefined error..

Issue(s)

#18648

How to test or reproduce

1. Enable SAML auth on the admin panel settings
2. Choose user without 'email' field provided by the SAML auth
3. Try to login with this user

Screenshots

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Hotfix (a major bugfix that has to be merged asap)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Changelog

Fixed the SAML login undefined error message

Further comments