title: GETTING ERROR : Warning: Failed prop type: Invalid prop `children` supplied to `Form`, expected a ReactNode
body: <p>I am making a simple demo of <code>useContext</code> using <code>final-form</code>.I am getting this warning </p>
  
  <p><strong><code>Warning: Failed prop type: Invalid prop</code>children<code>supplied to</code>Form<code>, expected a ReactNode.</code></strong></p>
  
  <p>here is my code
  <a href="https://codesandbox.io/s/github/test-gitt" rel="nofollow noreferrer">https://codesandbox.io/s/github/test-gitt</a></p>
  
  <p>step to reproduce my issue or warning</p>
  
  <ol>
  <li>run the application .A button is displayed . Click on button.it shows another page having a button.</li>
  <li>click again the button with console open <code>contrl+alt+I</code>.</li>
  </ol>
  
  <p>you will this warning why ?</p>
  
  <pre><code>&lt;BrowserRouter&gt;
          &lt;LoadingProvider&gt;
              &lt;Router/&gt;
          &lt;/LoadingProvider&gt;
      &lt;/BrowserRouter&gt;
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/769p4.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/769p4.png" alt="enter image description here"></a></p>
  
  <p>any update ?</p>