As far as I have seen, there has not been a vanishing closet in Hogwarts. It would be an easy way to get through the wards. But, there was the Come and Go Room which did house all the lost items throughout the years. It’s possible that the other closet is there. It left a bitter taste in my mouth at the thought of helping this, but I didn’t want Draco to be hurt for not being able to complete the task. He seemed far too innocent for this war. It was a good thing that the Hogwarts defense system still worked. It wasn’t designed to repel armies for nothing.