Make clients exit orderly when there is no connection
diff --git a/clients/flower.c b/clients/flower.c
index 9054c0f..b919cf5 100644
--- a/clients/flower.c
+++ b/clients/flower.c
@@ -124,6 +124,10 @@
 	struct display *d;
 
 	d = display_create(&argc, &argv, NULL);
+	if (d == NULL) {
+		fprintf(stderr, "failed to create display: %m\n");
+		return -1;
+	}
 
 	flower.x = 512;
 	flower.y = 384;