This can be quite tough. It means that the jQuery library is not correctly loaded. Look at other update widgets and see how they do that.
Take a look at the widget boilerplate that by default includes jQuery.
The problem here is that the libraries are minified. I think they work correctly when not bundled, but when it's bundled, the minified scripts break. I have already created a fork to fix this problem, but it does not seem to work...