Production build broken

[samhh]

This is due to Uglify not supporting ES6+.

Take -p out of the build command and manually pass the NODE_ENV instead if needed.

[JeremyRH]

Babel has the option to transpile to es5 always.
https://github.com/babel/babel-preset-env#forcealltransforms

[samhh]

In that case we could simply change the env preset to ES5, but that's going to result in worse code/larger payloads being delivered to browsers that we can assume will be modern based upon our browser support. babili is already in there to handle uglification/minification so that -p is unneeded anyway (once env var is passed in differently). This issue was more a reminder for me than anything else. :-)