Role Manager: Trying to get property of non-object

[tyamz]

UPDATE: I believe this is a bug. If you change the name of an existing group from the User Groups Manager by RainLab, it can cause the following error when trying to access the Role Manager? I'm not at all sure why this happens. I had no roles assigned to the groups that I changed.

Trying to get property of non-object /var/www/html/plugins/clake/userextended/controllers/Roles.php on line 127

Which corresponds to:

$unassignedUsers = UsersGroups::byUsersWithoutRole($this->vars['selectedGroup']->code)->get();