ReferenceError: fetch is not defined

[mubarak23]

Trying to generate an invoice, but i getting this error

import { LightningAddress } from "@getalby/lightning-tools";

if (!process.env.MERCHANT_LN_ADDRESS) {
  throw new Error(
    "Merchant's Lightning address environment variable is not defined"
  );
}

const ln = new LightningAddress(process.env.LN_ADDRESS)

await ln.fetch()
console.log('await ln.fetch()',  await ln.fetch())

error
ReferenceError: fetch is not defined