title: npm start not working after installation of webpack and babel
body: <p>I have created an app in react-redux. After that I have installed babel and webpack using below link.</p>
  
  <blockquote>
    <p><a href="https://medium.com/@siddharthac6/getting-started-with-react-js-using-webpack-and-babel-66549f8fbcb8" rel="nofollow noreferrer">https://medium.com/@siddharthac6/getting-started-with-react-js-using-webpack-and-babel-66549f8fbcb8</a></p>
  </blockquote>
  
  <p>Below is my webpack.config.js file:</p>
  
  <pre><code>const path = require('path');
  const HWP = require('html-webpack-plugin');
  
  module.exports = {
     entry: path.join(__dirname, '/src/index.js'),
     output: {
         filename: 'build.js',
         //path: path.join(__dirname, '/dist')},
         path: path.resolve(__dirname, 'build'),
     },
     module:{
         rules:[{
            test: /\.js$/,
            exclude: /node_modules/,
            loader: 'babel-loader'
         }]
     },
     plugins:[
         new HWP(
            {template: path.join(__dirname,'/src/index.html')}
         )
     ]
  }
  </code></pre>
  
  <blockquote>
    <p>I'm getting below error when I run the "npm start"</p>
  </blockquote>
  
  <pre><code>&gt; my-app@0.1.0 start /var/www/html/SFL
  &gt; webpack-dev-server — mode development — open — hot
  
  ✖ ｢wds｣: Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema.
   - configuration.entry should be one of these:
     function | object { &lt;key&gt;: non-empty string | [non-empty string] } | non-empty string | [non-empty string]
     -&gt; The entry point(s) of the compilation.
     Details:
      * configuration.entry should be an instance of function
        -&gt; A Function returning an entry object, an entry string, an entry array or a promise to these things.
      * configuration.entry['main'] should be a string.
        -&gt; The string is resolved to a module which is loaded upon startup.
      * configuration.entry['main'] should not contain the item '—' twice.
      * configuration.entry should be a string.
        -&gt; An entry point without name. The string is resolved to a module which is loaded upon startup.
      * configuration.entry should be an array:
        [non-empty string]
  npm ERR! code ELIFECYCLE
  npm ERR! errno 1
  npm ERR! my-app@0.1.0 start: `webpack-dev-server — mode development — open — hot`
  npm ERR! Exit status 1
  npm ERR! 
  npm ERR! Failed at the my-app@0.1.0 start script.
  npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
  </code></pre>
  
  <p>I'm trying to solve above error. Is there any other way to solve this error?</p>