Fix crash disabling monitor with locked surface

(cherry picked from commit d1880b4422)

Makefile

@@ -61,6 +61,7 @@ dist: clean
 
 install: dwl
 	mkdir -p $(DESTDIR)$(PREFIX)/bin
+	rm -f $(DESTDIR)$(PREFIX)/bin/dwl
 	cp -f dwl $(DESTDIR)$(PREFIX)/bin
 	chmod 755 $(DESTDIR)$(PREFIX)/bin/dwl
 	mkdir -p $(DESTDIR)$(MANDIR)/man1

dwl.c

@@ -716,6 +716,8 @@ cleanupmon(struct wl_listener *listener, void *data)
 	wl_list_remove(&m->frame.link);
 	wl_list_remove(&m->link);
 	wl_list_remove(&m->request_state.link);
+	if (m->lock_surface)
+		destroylocksurface(&m->destroy_lock_surface, NULL);
 	m->wlr_output->data = NULL;
 	wlr_output_layout_remove(output_layout, m->wlr_output);
 	wlr_scene_output_destroy(m->scene_output);
@@ -1177,7 +1179,6 @@ void
 destroydecoration(struct wl_listener *listener, void *data)
 {
 	Client *c = wl_container_of(listener, c, destroy_decoration);
-	c->decoration = NULL;
 
 	wl_list_remove(&c->destroy_decoration.link);
 	wl_list_remove(&c->set_decoration_mode.link);
@@ -3143,7 +3144,7 @@ sethints(struct wl_listener *listener, void *data)
 {
 	Client *c = wl_container_of(listener, c, set_hints);
 	struct wlr_surface *surface = client_surface(c);
-	if (c == focustop(selmon))
+	if (c == focustop(selmon) || !c->surface.xwayland->hints)
 		return;
 
 	c->isurgent = xcb_icccm_wm_hints_get_urgency(c->surface.xwayland->hints);