I found a fix for this, with the help of another response in fast.ai forums: Open the notebook in JupyterLabs while running on Paperspace.
Here’s how I got there…
I have been having problems with Lesson 2 in multiple environments, including VS Code on my Mac, PC (Windows), PC (WSL), and Paperspace. In each case I have been getting different Python errors in different locations. Paperspace seemed to work the most reliably overall, but I encountered the ImageClassifierCleaner bug there (i.e. JavaScript errors displaying widgets). I tried upgrading and downgrading different Python libraries thinking I just needed to find the right combo of library versions, but that didn’t fix anything and probably made things worse. (I ended up doing a clean Python + fastbook install on my Mac to make sure things were stable.)
None of this was working, and I came across a forum post from @evanemolo (ImageClassifierCleaner UI doesn’t update - Part 1 2022 - fast.ai Course Forums) that recommends opening the notebook in a JupyterLab notebook. This is an option on the left side of your Paperspace window. Everything works after I did this. Apparently the default Paperspace notebook has some things that don’t play nice with fastbook.
Seems like the fastbook repo needs some love to make it more reliable in different environments.