Fixes for [#30930], [#30932]

[#30930] Fatal error with JHelper::setUserGroups
Fix small mistake introduced in e98350c09523de6b4a9fe151efef9a621ba88250.

[#30932] Missing variable in gmail authentication
Line 50 got deleted by accident in 4fe8a29e94b81c62f51f75482426e2365592906b.