Ahoy! A bit of an update regarding that issue: the issue turns out to be how the book plugin tries to find it's name. Since it's loaded via nwjs' built in mechanism (since the compiled version of the plugin can't be loaded through normal means), trying to find the name via looking up in the document, it will return null, thus breaking it during launch.
This was certainly a tough bug to figure out. But it was a pattern that I saw in other plugin. Took me a while to notice it here as well.
The current workaround for this is to hardcode the name.