ipc: collapse multi-container command results

Match i3's behavior and only return one status response per command,
even if it applies to several nodes.

Also returns an error if the criteria returns an empty match.

Closes #4483

sway/commands.c

@@ -284,17 +284,32 @@ list_t *execute_command(char *_exec, struct sway_seat *seat,
 				free_argv(argc, argv);
 				goto cleanup;
 			}
+		} else if (views->length == 0) {
+			list_add(res_list,
+					cmd_results_new(CMD_FAILURE, "No matching node."));
 		} else {
+			struct cmd_results *fail_res = NULL;
 			for (int i = 0; i < views->length; ++i) {
 				struct sway_view *view = views->items[i];
 				set_config_node(&view->container->node);
 				struct cmd_results *res = handler->handle(argc-1, argv+1);
-				list_add(res_list, res);
-				if (res->status == CMD_INVALID) {
-					free_argv(argc, argv);
-					goto cleanup;
+				if (res->status == CMD_SUCCESS) {
+					free_cmd_results(res);
+				} else {
+					// last failure will take precedence
+					if (fail_res) {
+						free_cmd_results(fail_res);
+					}
+					fail_res = res;
+					if (res->status == CMD_INVALID) {
+						list_add(res_list, fail_res);
+						free_argv(argc, argv);
+						goto cleanup;
+					}
 				}
 			}
+			list_add(res_list,
+					fail_res ? fail_res : cmd_results_new(CMD_SUCCESS, NULL));
 		}
 		free_argv(argc, argv);
 	} while(head);