[Bug]: DAV login with email address: Call to a member function getUID() on null

[ChristophWurst]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

https://nextcloud-gmbh.sentry.io/issues/4892762928 popped up with the deployment of a 28.0.2.0 setup.

Steps to reproduce

1. Send DAV request using the email address as username

Expected behavior

Login works

Installation method

None

Nextcloud Server version

28

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

[ChristophWurst]

If the regression is from within the user session, there are only three new commits since 28.0.1

980b14f -> \OC\User\Session::tryTokenLogin is not used by the dav auth plugin
360e7ff
1712df7

[ChristophWurst]

1712df7 actually sounds super relevant

👀 @juliushaertl

[ChristophWurst]