fix(swarm): guard getApplicationInfo against empty appNames array

When called with an empty array, `docker service ps` receives no
SERVICE argument and fails with "requires at least 1 argument".
Return early with [] when appNames is empty.

packages/server/src/services/docker.ts

@@ -453,6 +453,9 @@ export const getApplicationInfo = async (
 	appNames: string[],
 	serverId?: string,
 ) => {
+	if (appNames.length === 0) {
+		return [];
+	}
 	try {
 		let stdout = "";
 		let stderr = "";