Fix crash disabling monitor with locked surface

Makefile

@@ -61,7 +61,6 @@ 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

@@ -1179,6 +1179,7 @@ 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);
@@ -3144,7 +3145,7 @@ 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) || !c->surface.xwayland->hints)
+	if (c == focustop(selmon))
 		return;
 
 	c->isurgent = xcb_icccm_wm_hints_get_urgency(c->surface.xwayland->hints);