Avoid using a nullptr root in Tree._range_click_timeout().
Avoid using a nullptr root in Tree._range_click_timeout().

Fixes #46648

(cherry picked from commit f17f3f8830088304d7144a8eb3c25d9956f3aa20)

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