This is going to be really useful for folks looking to get started on lightning.

Small nit about language: afaict you don't start a background process for listening to invoice events.

async function initLndClient() {
  await lndClient.connect();

  const subscription = await lndClient.services.Lightning.subscribeInvoices();
  subscription.on("data", (invoice) => {
    console.log("Lightning Invoice Event");
    console.log(invoice);
  });
}
initLndClient();

In nodejs this just inserts an event listener in node's run loop. It kind of behaves like a background process, but if you kill your nodejs process, this event logging stops.