Keep to show current script when closing all docs

also fix error when removing multiple tabs from TabContainer at same frame.
like closing multiple docs at once.

Fix #16403

scene/gui/tab_container.h

@@ -62,6 +62,7 @@ private:
 	Vector<Control *> _get_tabs() const;
 	int _get_tab_width(int p_index) const;
 	void _on_theme_changed();
+	void _update_current_tab();
 
 protected:
 	void _child_renamed_callback();