How to POST data from Puppeteer to Google Apps Script web app API endpoint in node.js?

I have a Puppeteer scraping script that successfully fetches my target data. Now, I want to post the data in my Google Apps Script web app and read it with doPost() in GAS. I expect to see the data in my Google Sheets file but instead I get the following error.

TimeoutError: Navigation timeout of 30000 ms exceeded at /Users/path/to/node_modules/puppeteer/lib/LifecycleWatcher.js:142:21 -- ASYNC -- at Frame. (/Users/path/to/node_modules/puppeteer/lib/helper.js:111:15) at Page.goto (/Users/path/to/node_modules/puppeteer/lib/Page.js:675:49) at Page. (/Users/path/to/node_modules/puppeteer/lib/helper.js:112:23) at /Users/path/to/proto.js:215:37 at processTicksAndRejections (internal/process/task_queues.js:93:5) { name: 'TimeoutError' }

What am I doing wrong?

  const pagePost = await browser.newPage();

  ...
  postUrl = 'https://script.google.com/macros/s/abcdexyz123/exec' // GAS endpoint, tested and working
  itemsAsCsv = // csv data
  ...

  // Allows you to intercept a request; must appear before
  // your first page.goto()
  await pagePost.setRequestInterception(true);

  // Request intercept handler... will be triggered with 
  // each page.goto() statement
  pagePost.on('request', interceptedRequest => {

      // Here, is where you change the request method and 
      // add your post data
      var data = {
          method: POST,
          postData: itemsAsCsv,
      };

      // Request modified... finish sending! 
      interceptedRequest.continue(data);
  });

  // Navigate, trigger the intercept, and resolve the response
  try {
    const response = await pagePost.goto(postUrl);     
    const responseBody = await response.text();
    console.log(responseBody);
  } catch(e) {
    console.log(e)   
  }

  // // Close the browser - done! 
  // await browser.close();

  // end POST

  await browser.close();