Cannot delete Projects with team members

Created by: pulse00

A minor issue if you know how to solve it, but anyways:

When you delete a project that still has teammembers, you'll end up with a 500 error and the following log entry:

NoMethodError (undefined method `name' for nil:NilClass):
app/observers/system_hook_observer.rb:45:in `after_destroy'
app/controllers/admin/projects_controller.rb:58:in `destroy'

Navigating to the project on http://gitlab.example.com/admin/projects/project-name/edit and removing all users from the project resolves the issue.