To check if an autoload was freed, it currently checks for `scene_file_path` by using `Node::is_instance()`, and not if it was actually freed or not. I fixed it by checking if the node is inside the tree, as a freed node cannot be inside the tree anyway.
This sometimes caused crashes when plugins handle their autoloads weirdly (e.g PhantomCamera), which this fixes.
(cherry picked from commit 6848ea595e91cf6a1d5dc4f88c964f8d1f6de178)
GabCoolGuy
8ef3779eed