If a form script is loaded using an XHR from a web server, it is executed using eval(). To debug it, you need to use browser-specific debugger extensions.

Debugging Form Scripts in Google Chrome

If you are using the Google Chrome debugger, you can add the debugger; directive to the source code of the script:

<form role="form">

  <script cam-script type="text/form-script">
    debugger;
  </script>

</form>