title: react-router-dom Failed prop type: Invalid prop `exact` of type `string`
body: <p>I met some strange warning when I try to use <code>&lt;Route /&gt;</code> component. Please pay your attention into a line <code>&lt;Route exact={"true"} .../&gt;</code> which makes strange browser warnings described beneath code sample. </p>
  
  <pre><code>ReactDOM.render(
      &lt;Provider store={appStore}&gt;
          &lt;ConnectedRouter store={appStore} history={history}&gt;
              &lt;BrowserRouter&gt;
                  &lt;Switch&gt;
                      &lt;Route exact={"true"} path="/" component={App}/&gt;
                      &lt;Route render={() =&gt; &lt;h1&gt;404, not found&lt;/h1&gt;} /&gt;
                  &lt;/Switch&gt;
              &lt;/BrowserRouter&gt;
          &lt;/ConnectedRouter&gt;
     &lt;/Provider&gt;,
  document.getElementById('root'));
  </code></pre>
  
  <p>Browser console says me next:</p>
  
  <blockquote>
    <p>Warning: Failed prop type: Invalid prop <code>exact</code> of type <code>string</code>
    supplied to <code>Route</code>, expected <code>boolean</code>.
        in Route (at src/index.tsx:19) index.js:1452</p>
  </blockquote>
  
  <p>And the following warning after prev one is absolutely apposite by text logic</p>
  
  <blockquote>
    <p>Warning: Received <code>true</code> for a non-boolean attribute <code>exact</code>.</p>
    
    <p>If you want to write it to the DOM, pass a string instead:
    exact="true" or exact={value.toString()}.
        in a (created by Context.Consumer)
        in Link (at App.tsx:25)
        in header (at App.tsx:11)
        in div (at App.tsx:10)
        in App (created by Context.Consumer)
        in Route (at src/index.tsx:19)
        in Switch (at src/index.tsx:18)
        in Router (created by BrowserRouter)
        in BrowserRouter (at src/index.tsx:17)
        in Router (created by ConnectedRouter)
        in ConnectedRouter (at src/index.tsx:16)
        in Provider (at src/index.tsx:15)</p>
  </blockquote>
  
  <p><a href="https://i.stack.imgur.com/hdtvN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hdtvN.png" alt="react-router-dom Failed prop type: Invalid prop &#39;exact&#39; of type &#39;string&#39;"></a>
  Could you please help me with this issue. Tnx!</p>
  
  <p>described example are located here in opensource prj <a href="https://github.com/gyerts/react/blob/master/starters/typescript-scss-redux/src/index.tsx#L19" rel="nofollow noreferrer">https://github.com/gyerts/react/blob/master/starters/typescript-scss-redux/src/index.tsx#L19</a></p>