I'm trying to build a vagrant server for dabbling with elixir and phoenix, but after installing all requirements and dependencies, and on running `mix phoenix.server` I'm getting the following error:

> 
> error: Compiling of 'web/static/js/app.js' failed. Couldn't find preset "es2015" relative to directory "web/static/js" ;
> 
> 
> 

I'm not sure of the context of 'preset' here, I'm hoping a more seasoned phoenix user will know what it's getting at.

Some cursory Google's gave me nothing, other than it might be something to do with babel.

Edit: I just tried installing what I assume to be the missing package, `sudo npm install babel-preset-es2015 -g`, but it hasn't resolved the error.