Make clients exit orderly when there is no connection
diff --git a/clients/image.c b/clients/image.c
index cf98266..8f30c4a 100644
--- a/clients/image.c
+++ b/clients/image.c
@@ -244,6 +244,10 @@
 	int i;
 
 	d = display_create(&argc, &argv, option_entries);
+	if (d == NULL) {
+		fprintf(stderr, "failed to create display: %m\n");
+		return -1;
+	}
 
 	for (i = 1; i < argc; i++) {
 		struct image *image;