Cannot read property 'replace' of null

[trueinviso]

I keep getting this error when I try to run the server:

$ npm start

> auth0-react-sample@1.0.0 start /Users/trueinviso/side_projects/react-user-authentication
> npm-run-all --parallel dev-server

ERROR: Cannot read property 'replace' of null
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! auth0-react-sample@1.0.0 start: `npm-run-all --parallel dev-server`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the auth0-react-sample@1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

It seems to be related to this webpack issue:

webpack/webpack-dev-server#381

But I'm not sure, I've tried changing webpack versions with no luck.