redux-devtools/packages/redux-devtools-app/src/index.js

import React from 'react';
import { render } from 'react-dom';
import App from './app';

render(
  <App />,
  document.getElementById('root')
);

if (module.hot) {
  // https://github.com/webpack/webpack/issues/418#issuecomment-53398056
  module.hot.accept(err => {
    if (err) console.error(err.message);
  });

  /*
    module.hot.accept('./app', () => {
      const NextApp = require('./app').default;
      render(
        <NextApp />,
        document.getElementById('root')
      );
    });
   */
}