test.html

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8" />
  <title>ImageData test</title>
</head>
<body>
  <script type="module">
    function success () {
      document.body.style.backgroundColor = 'green'
    }

    function error (err) {
      document.body.style.backgroundColor = 'red'
      document.body.textContent = err.stack
    }

    import("./test.js").then(success, error)
  </script>
</body>
</html>