I merged JSSDemo a bit eagerly, even though I knew it needed some fixing up because I wanted to ensure @kof got contributor credit, and it seemed to be working when I peeked over his shoulder. However, one of the things that needed fixing was adding jss as a dependency to package.json.
That depends on is-observable, which seems to conflict with the isObservable defined in our type guards (and break all the demos). This is probably a bug in Pundle.
JSS is an exciting option, because it gives us a way to animate React components without accidentally rerendering them. However, until I have a demo that I can verify works with our demo site, I'm rolling this back.