I'm trying to get the line_items of the checkout session in Stripe so that I can send an email consisting of the product download link but unfortunately, When I try to retrieve the line_items in the checkout_session I get a null value.

Frontend: Next.js

Here is my code in /pages/api/webhooks/index.ts:

Check the line: 77

import { buffer } from "micro";
import Cors from "micro-cors";
import { NextApiRequest, NextApiResponse } from "next";

import Stripe from "stripe";
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!, {
  // https://github.com/stripe/stripe-node#configuration
  apiVersion: "2020-08-27",
});

const webhookSecret: string = process.env.STRIPE_WEBHOOK_SECRET!;

// Stripe requires the raw body to construct the event.
export const config = {
  api: {
    bodyParser: false,
  },
};

const cors = Cors({
  allowMethods: ["POST", "HEAD"],
});

const webhookHandler = async (req: NextApiRequest, res: NextApiResponse) => {
  if (req.method === "POST") {
    const buf = await buffer(req);
    const sig = req.headers["stripe-signature"]!;

    let event: Stripe.Event;

    try {
      event = stripe.webhooks.constructEvent(
        buf.toString(),
        sig,
        webhookSecret
      );
    } catch (err) {
      // On error, log and return the error message.
      console.log(`❌ Error message: ${err.message}`);
      res.status(400).send(`Webhook Error: ${err.message}`);
      return;
    }

    // Successfully constructed event.
    console.log(`✅ Success: ${event.id}`);

    // Cast event data to Stripe object.
    if (event.type === "payment_intent.created") {
      const paymentIntent = event.data.object as Stripe.PaymentIntent;
      console.log(`