npm run start fails

[sgm183]

@kenny-hibino
I'm receiving the following error after running npm run start:

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id:2): TypeError: "listener" argument must be a function

I've run npm install with zero errors and one warn:

material-ui@0.15.4 requires a peer of react-top-event-plugin@^1.0.0 but none was installed

Also, I have the Rails API running on localhost:5000.

Any help would be appreciated. Thanks!