I just upgraded and got 'Failed to load module script: The server responded with a non-JavaScript MIME type of "text/plain".' from my S3 through CloudFront. Seems like it's not adding 'type="text/javascript"' to in index.html. When adding this manually, everything works. Just FYI if others upgrade and seem to get the same errors.
Modules, however, enforce strict mime type checking. As the comment below suggests, you should make sure your static file hosting serves JavaScript with the correct mime type.