check parent surface before it is destroyed

sway/desktop/xwayland.c

@@ -95,7 +95,7 @@ static void unmanaged_handle_unmap(struct wl_listener *listener, void *data) {
 	if (seat->wlr_seat->keyboard_state.focused_surface == xsurface->surface) {
 		// This simply returns focus to the parent surface if there's one available.
 		// This seems to handle JetBrains issues.
-		if (xsurface->parent &&
+		if (xsurface->parent && xsurface->parent->surface &&
 				wlr_surface_is_xwayland_surface(xsurface->parent->surface)) {
 			struct wlr_xwayland_surface *next_surface =
 				wlr_xwayland_surface_from_wlr_surface(xsurface->parent->surface);