You might be encountering this when running the code due to a known bug in Google Apps Script. You may see the error message when you inspect the modal dialog and click the console.

The error message is:

Uncaught TypeError: vb.X is not a constructor.

There's a bug report about this on Google's Issue Tracker. Since you seem to be affected as well, you can add a thumbs-up ("+1") to the report to indicate that you are impacted as well and you may subscribe by clicking on the star next to the issue number in order to receive updates. This will help Google prioritize fixing the bug.