TL;DR: update npm to > 3
Installing the node LTS package installs node 4.5 and npm 2.something. According to a couple of other posts I found via google, installing npm > 3 fixes this.
Either using npm install npm -g or installing a later version of node via NVM fixed this issue for me.
At the time of writing, I'm still not sure what the official version of node for this project is meant to be.