title: webpack-dev-server opens localhost:8080/undefined
body: <p>When I run <code>$ npm run dev</code> (<code>"dev": "webpack-dev-server"</code>) it opens localhost:8080/undefined instead of localhost:8080 or at least localhost:8080/index.html</p>
  
  <p>webpack-config.js devServer part:</p>
  
  <p>devServer: {</p>
  
  <pre><code>    contentBase: path.join(__dirname, 'dist'),
  
      compress: true,
  
      stats: "errors-only",
  
      hot: true,
  
      open: true
  </code></pre>
  
  <p>If I delete the /undefined part of the URL it works properly even the hot module replacement so it's not a big problem; just want to know why is that happening.</p>
  
  <p>Edit: Im on MacOS</p>
  
  <p>Edit2: Console info when <code>npm run dev</code>:</p>
  
  <p><code>Project is running at http://localhost:8080/
  webpack output is served from /
  Content not from webpack is served from /Users/cozarkd/folders/dist
  webpack: wait until bundle finished: /undefined
  webpack: Compiled successfully.</code></p>
  
  <p>Ty</p>