@CyanPrime not sure how that's fixed it as your route inside theme.less doesn't actually point to the vanilla template. For that file to point at vanilla, you'd be looking at ../../../nodebb-theme-vanilla, but if it works then, so be it.
@a_5mith, it used to do something, right?
Yeah it used to list all the plugins in npm and (I think) allow you to install them. But this was added to core a fair few versions back. Around 0.3 or 0.4. I hope that's the plugin I'm thinking of.