Chrome extension using Drive API returns incomplete search

I’m working on a Chrome Extension with the Drive API v3. My OAuth, API key and client_id are working fine. I’m having trouble fetching any data.

I used this as a starting point and it works fine for the People API. I modified the oauth.js code to this:

window.onload = function() {
  document.querySelector('button').addEventListener('click', function() {
  chrome.identity.getAuthToken({interactive: true}, function(token) {
  let init = {
    method: 'GET',
    async: true,
    headers: {
      Authorization: 'Bearer ' + token,
      'Content-Type': 'application/json'
    },
    'contentType': 'json'
  };
  fetch(
    //'https://www.googleapis.com/drive/v3/files?mimeType!='application/vnd.google-apps.folder'',
    //'https://www.googleapis.com/drive/v3/files?q=name%20contains%20'Yamaha'',
    //'https://www.googleapis.com/drive/v3/files?name='Spices'',
    'https://www.googleapis.com/drive/v3/files?q='0Bxl5Z50oMH4MX2E0UXdhQUdUbGs'',
    init)
    .then((response) => response.json())
    .then(response => {
      console.log(JSON.stringify(response))
      console.log("Done stringify");
      console.log(response);
      console.log("Done response");
      
    })
   });
  });
 };

The commented lines are attempts at different fetch syntaxes.

For each of these attempts, I do not get any console errors but instead I get the following:

What is the missing piece? Ideally, I’d like to get all the files/folders, their ids and names!