title: Error: v(...): A valid React element (or null) must be returned. You may have returned undefined, an array or some other invalid object
body: <p>I am new to <code>react</code> and <code>react-router</code>. I am migrating from <code>react-router v2.8.1 to v4.1.1</code>. I am getting this error in the following code. Please help. Thanks in advance. </p>
  
  <pre><code>const reactRouterDom = require&lt;any&gt;('react-router-dom');
  let {BrowserRouter, Route} = reactRouterDom;
  ReactDOM.render(
      &lt;Provider store={store}&gt;
          &lt;BrowserRouter onUpdate={scrollToTop}&gt;
              &lt;Route path="/" component={App} /&gt;
          &lt;/BrowserRouter&gt;
      &lt;/Provider&gt;, document.getElementById('app')
  );
  </code></pre>