webpack: Uncaught TypeError: __webpack_require__(...).ensure is not a function

I’m not able to load my chunks on demand because require.ensure is not defined. What I’m getting wrong here?

if (!global.Intl) {
  require.ensure(["intl"], function (require) {
    require('intl');
  });
}

produces:

Uncaught TypeError: __webpack_require__(...).ensure is not a function

I’m loading CommonsChunkPlugin

new webpack.optimize.CommonsChunkPlugin("vendor", 'vendor.js'),

and injecting vendor.js correctly into my page along with the main chunks.

I’m using the following webpack versions:

“webpack”: “^1.12.9”, “webpack-dev-middleware”: “^1.4.0”, “webpack-hot-middleware”: “^2.5.0”

and my webpack.prod.config.js

require('babel/polyfill');

// Webpack config for creating the production bundle.
var path = require('path');
var webpack = require('webpack');
var CleanPlugin = require('clean-webpack-plugin');
var ExtractTextPlugin = require('extract-text-webpack-plugin');
var strip = require('strip-loader');

var relativeAssetsPath = '../static/dist';
var assetsPath = path.join(__dirname, relativeAssetsPath);

// https://github.com/halt-hammerzeit/webpack-isomorphic-tools
var WebpackIsomorphicToolsPlugin = require('webpack-isomorphic-tools/plugin');
var webpackIsomorphicToolsPlugin = new WebpackIsomorphicToolsPlugin(require('./webpack-isomorphic-tools'));

module.exports = {
  devtool: 'source-map',
  context: path.resolve(__dirname, '..'),
  entry: {
    'main': [
      'bootstrap-sass!./src/theme/bootstrap.config.prod.js',
      'font-awesome-webpack!./src/theme/font-awesome.config.prod.js',
      './src/client.js'
    ],
    intl: [
      'intl'
    ]
  },
  output: {
    path: assetsPath,
    filename: '[name]-[chunkhash].js',
    chunkFilename: '[name]-[chunkhash].js',
    publicPath: '/dist/'
  },
  module: {
    loaders: [
      { test: /\.js$/, exclude: /node_modules/, loaders: [strip.loader('debug'), 'babel']},
      { test: /\.(yml|yaml)$/, loader: 'json-loader!yaml-loader' },
      { test: /\.json$/, loader: 'json-loader' },
      { test: /\.less$/, loader: ExtractTextPlugin.extract('style', 'css?modules&importLoaders=2&sourceMap!autoprefixer?browsers=last 2 version!less?outputStyle=expanded&sourceMap=true&sourceMapContents=true') },
      { test: /\.scss$/, loader: ExtractTextPlugin.extract('style', 'css?modules&importLoaders=2&sourceMap!autoprefixer?browsers=last 2 version!sass?outputStyle=expanded&sourceMap=true&sourceMapContents=true') },
      { test: /\.woff(\?v=\d+\.\d+\.\d+)?$/, loader: "url?limit=10000&mimetype=application/font-woff" },
      { test: /\.woff2(\?v=\d+\.\d+\.\d+)?$/, loader: "url?limit=10000&mimetype=application/font-woff" },
      { test: /\.ttf(\?v=\d+\.\d+\.\d+)?$/, loader: "url?limit=10000&mimetype=application/octet-stream" },
      { test: /\.eot(\?v=\d+\.\d+\.\d+)?$/, loader: "file" },
      { test: /\.svg(\?v=\d+\.\d+\.\d+)?$/, loader: "url?limit=10000&mimetype=image/svg+xml" },
      { test: webpackIsomorphicToolsPlugin.regular_expression('images'), loader: 'url-loader?limit=10240' }
    ]
  },
  progress: true,
  resolve: {
    modulesDirectories: [
      'src',
      'node_modules'
    ],
    extensions: ['', '.json', '.js']
  },
  plugins: [
    new webpack.optimize.CommonsChunkPlugin("vendor", '[name]-[chunkhash].js'),
    new CleanPlugin([relativeAssetsPath]),

    // css files from the extract-text-plugin loader
    new ExtractTextPlugin('[name]-[chunkhash].css', {allChunks: true}),
    new webpack.DefinePlugin({
      __CLIENT__: true,
      __SERVER__: false,
      __DEVELOPMENT__: false,
      __DEVTOOLS__: false
    }),

    // ignore dev config
    new webpack.IgnorePlugin(/\.\/dev/, /\/config$/),

    // set global vars
    new webpack.DefinePlugin({
      'process.env': {
        // Useful to reduce the size of client-side libraries, e.g. react
        NODE_ENV: JSON.stringify('production')
      }
    }),

    // optimizations
    new webpack.optimize.DedupePlugin(),
    new webpack.optimize.OccurenceOrderPlugin(),
    /*new webpack.optimize.UglifyJsPlugin({
      compress: {
        warnings: false
      }
    }),*/
    webpackIsomorphicToolsPlugin
  ]
};