Meteor use webpack: Cannot find the entry point “index.js” for the web

As I asked on https://stackoverflow.com/questions/45432200/meteor-webpack-cannot-find-the-entry-point-index-js-for-the-web

I am trying to use webpack with meteor app based on pup boilerplate.

What I did was to follow the https://medium.com/@SamCorcos/meteor-webpack-from-the-ground-up-f123288c7b75 tutorial and create the following webpack.config.js file:

[
module.exports = {
  entry: {
    web: ['./client/main.js', './server/main.js'],
    vendors: ['react']
  },
  resolve: {
    extensions: ['', '.js', '.jsx', '.json']
  },
  module: {
    loaders: [
      { 
        test: /\.jsx?$/,
        loader: 'babel',
        exclude: /node_modules/,
        query:
        {
          presets:['es2015','react']
        }
      }
    ]
  }
}

But I get the following error when I try to run MONGO_URL=^mongodb_url^ meteor --port 1821 --settings settings-development.json

Cannot find the entry point “index.js” for the web

So I want some help to solve this prob. Can you help me?