About the shortest code I could write to render an image out from the Figma API and make it clear whether it is loading/has loaded.

figma-get-image-from-api.js

// About the shortest code I could write to render an image out from the Figma API and make it clear whether it is loading/has loaded.
// https://github.com/wolfr

// If you use this code please change to your own access token
const PERSONAL_ACCESS_TOKEN = ''; // Your personal access token here

function apiRequest(endpoint) {
    return fetch('https://api.figma.com/v1' + endpoint, {
        method: 'GET',
        headers: { "x-figma-token": PERSONAL_ACCESS_TOKEN }
    }).then(function(response) {
        return response.json();
    }).catch(function (error) {
        return { err: error };
    });
}

const fileKey = ''; // Your file key here
const nodeId =  '7%3A42' // Your node id here, example provided because the semicolon is encoded

apiRequest('/images/' + fileKey + '?ids=' + nodeId + '&scale=2&quality=jpg')
   .then(function (apiResponse) {
  
      var imgUrl = Object.entries(apiResponse.images)[0][1];
  
      // Create image and set its URL
      var img = document.createElement('img');
      img.setAttribute("src", imgUrl);
      document.body.appendChild(img);
  
      // Display a success message
      var p = document.createElement('p');
      p.innerHTML = 'Image loading OK';
      document.body.appendChild(p);
      document.querySelector('p:first-child').remove();

   });