User Confirmation is broken / update to femanager 5.1.1

Summary

If I try to confirm a user in the Frontend User Module, I receive an error.

Oops, an error occurred! Call to a member function sL() on null

Steps to reproduce

1. Open BE Module Frontend users
2. Switch to Tab "Admin confirmation"
3. try to approve a user

Acceptence Criterias

• confirmation of a user works a again

Relevant logs and/or screenshots

Possible fixes

I think, one of the hooks can be the cause