xwayland: destroy map_link on window destroy

src/xwayland/xwm.rs

@@ -1883,6 +1883,7 @@ impl Wm {
         // log::info!("xwm destroy_notify {}", event.window);
         data.destroyed.set(true);
         data.stack_link.borrow_mut().take();
+        data.map_link.take();
         if let Some(sid) = data.surface_id.take() {
             self.windows_by_surface_id.remove(&sid);
         }