Notice: Undefined index: #default_value in _menu_views_form_alter() line 196

here's the whole error message:

Notice: Undefined index: #default_value in _menu_views_form_alter() (line 196 of C:\xampp\htdocs\xxx\sites\all\modules\xxx\menus\menu_views\menu_views.admin.inc)

any ideas on why this is happening? didn't see this message reported :\

update: sorry i forgot to add that this message is only triggered in each and every menu items' edit page. doesn't matter which menu the item may be. it's happening in all edit item pages.