shell: Remove lock/unlock listeners on shutdown
diff --git a/src/shell.c b/src/shell.c
index a44074d..fc49d70 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -2539,6 +2539,9 @@
 	if (shell->child.client)
 		wl_client_destroy(shell->child.client);
 
+	wl_list_remove(&shell->lock_listener.link);
+	wl_list_remove(&shell->unlock_listener.link);
+
 	free(shell->screensaver.path);
 	free(shell);
 }