It looks like you’re using the HTML widget export flow to use in your Pub – I recommend using the standard File > Export as HTML method to generate your HTML + resources folder. This way, it won’t think you are placing your Tumult Hype document within an iBook widget. Your current example includes some iBooks-only code which causes an error if it is not loaded in iBooks. It is looking for AppleWidgets.js (an Apple iBooks-only embedded JS file).
Can you let me know what device you’re testing this in and perhaps send screenshots of the issue you’re seeing?