Error appears when clicking edit for a menu link

This error appears:

 Notice: Undefined index: menu in _menu_per_role_form_alter() (line 78 of C:\xampp\htdocs\tecnotree\sites\all\modules\menu_per_role\menu_per_role.admin.inc).
    Notice: Undefined index: menu in _menu_per_role_form_alter() (line 81 of C:\xampp\htdocs\tecnotree\sites\all\modules\menu_per_role\menu_per_role.admin.inc).

But the page seems to load correctly (you can see the restrict item visibility options.)