Widget stops working after a couple days

I made a LibraryThing widget to display some books on a page of my website. It displayed correctly at first, but after a day or two it stopped loading on my website. I redid the whole widget from scratch and the same thing happened again — it's currently not loading. I'm not sure if I made some kind of mistake or if this is a problem on LibraryThing's end?

You can see the broken widget here: theodarling.com/divertissement

Assigning to Lucy.

I think we got it working again. But we'll have to see if it keeps working. I'll try to keep an eye, but let me know if you see it stop working again.

Thank you :) I appreciate you taking a look at it!