When switching to a different scene in the editor, the previous edited scene root will no longer have a parent and you'll see a pile of "Cannot call method 'is_ancestor_of' on a null value." errors from Godot. Unroll the one liner to add the parent null check and use some intermediate variables to remove duplicate method calls. Note that the is_inside_tree() call is dropped since it's redundant to checking if get_tree() returns null.