title: Require webpack bundle returns empty object
body: <p>Adding libraryTarget as suggested here: <a href="https://stackoverflow.com/questions/38289019/require-webpack-bundle-returns-empty-object">Require Webpack bundle -- returns empty object?</a> doesn't help.</p>
  
  <p>webpack.config.js:</p>
  
  <pre><code>var path = require('path');
  var webpack = require('webpack');
  
  module.exports = {
      target: "node",
      entry: './src/Api.ts',
      resolve: {
          extensions: ['.ts', '.tsx', '.js']
      },
      output: {
          path: path.join(__dirname, '/dist'),
          filename: 'bundle.min.js',
          libraryExport: "umd"  // tried several here
      },
      module: {
          rules: [
              {
                  test: /\.tsx?$/,
                  loader: 'awesome-typescript-loader'
              }
          ]
      }
  }
  </code></pre>
  
  <p>Api.ts:</p>
  
  <pre><code>export class Api {
      test(){
  
      }
  }
  </code></pre>
  
  <p>Then in another project I have (expressjs):</p>
  
  <pre><code>const mymodule = require('full_path/dist/bundle.min.js');
  console.log(mymodule) # always empty object
  </code></pre>
  
  <p>I was expecting to be able to do <code>mymodule.test()</code></p>