Fix crash on FileSystemDock's tree when trying to collapse or expand folder
Fix crash on FileSystemDock's tree when trying to collapse or expand folder

(cherry picked from commit e6145027efb4ad0a5615477c8df13761063c6157)

ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot