Easypost Node.js Example Difficulties?

I'm currently trying to implement the Easypost API however the example from the docs is console logging null on my front-end (localhost:3000)... does anyone know what I'm doing wrong? Thanks... First time using using firebase as well as easypost & react

functions/index.js:

const functions = require("firebase-functions");
const EasyPost = require("@easypost/api");

const api = new EasyPost(TEST_API_KEYS);

exports.buyShipping = functions.https.onCall((data, res) => {
  const shipment = new api.Shipment({
    from_address: {
      street1: "417 MONTGOMERY ST",
      street2: "FLOOR 5",
      city: "SAN FRANCISCO",
      state: "CA",
      zip: "94104",
      country: "US",
      company: "EasyPost",
      phone: "415-123-4567",
    },
    to_address: {
      name: "Dr. Steve Brule",
      street1: "179 N Harbor Dr",
      city: "Redondo Beach",
      state: "CA",
      zip: "90277",
      country: "US",
      phone: "4155559999",
    },
    parcel: {
      length: 8,
      width: 5,
      height: 5,
      weight: 5,
    },
  });

  shipment.save().then((s) => {
    s.buy(shipment.lowestRate()).then((result) => {
      return result;
    });
  });

  });
});

frontend:

import { initializeApp } from "firebase/app";
import { getFunctions, httpsCallable } from 'firebase/functions';

///

const app = initializeApp(firebaseConfig);
const functions = getFunctions(app);
const buyShipping = httpsCallable(functions, 'buyShipping')

const buy = async () => {              
       await buyShipping().then((result) => {
          /** @type {any} */
          console.log(result)
    })} 

///

<button onClick={buy}>Purchase</button>

I found the problem; I can't have a return within the shipment.save function in my firebase backend... this worked:

exports.buyShipping = functions.https.onCall((data, res) => {
  const shipment = new api.Shipment({
    from_address: {
      street1: "417 MONTGOMERY ST",
      street2: "FLOOR 5",
      city: "SAN FRANCISCO",
      state: "CA",
      zip: "94104",
      country: "US",
      company: "EasyPost",
      phone: "415-123-4567",
    },
    to_address: {
      name: "Dr. Steve Brule",
      street1: "179 N Harbor Dr",
      city: "Redondo Beach",
      state: "CA",
      zip: "90277",
      country: "US",
      phone: "4155559999",
    },
    parcel: {
      length: 8,
      width: 5,
      height: 5,
      weight: 5,
    },
  });

  const arrayData = shipment.save().then((s) => {
    return s;
  });
  return arrayData;
});