Known bug in webpack that you can add to the readme file.

[Mikael Sundström]

Without this in the current version, it will open in localhost:8080/undefined. I read that it was caused by late reading of the path. Maybe someone have the same issue.

devServer: {
    open: true,
    openPage: '', //add this to solve it
}

And nice tutorial!

[Petr Tichy]

Thanks Mikael, I did update the readme file.