title: webpack Object #<Object> has no method 'forEach'
body: <p>I'm going to start using react with babel with webpack but after run <code>webpack -w</code> it's not working and showing a error like </p>
  
  <pre><code>TypeError: Object #&lt;Object&gt; has no method 'forEach'
  </code></pre>
  
  <p>my webpack config </p>
  
  <pre class="lang-js prettyprint-override"><code>module.exports = {
      entry: "./app/components/Main.js",
      output: {
          filename: "public/bundle.js"
      },
      module: {
          loaders: {
              test: /\.js$/,
              exclude: /(node_modules|bower_components)/,
              loader: "babel-loader"
          }
      }
  }
  </code></pre>
  
  <p>my Main.js react file</p>
  
  <pre class="lang-js prettyprint-override"><code>var React = require('react');
  
  var Main = React.createClass({
  
      render: function() {
          return (
              &lt;div&gt;
                  Hello world!
              &lt;/div&gt;
          )
      }
  });
  
  React.render(&lt;Main /&gt;, document.getElementById('app'));
  </code></pre>
  
  <p>Please can anyone resolve this?</p>