title: Invariant Violation: Argument appears to not be a ReactComponent
body: <p>I need to find the <strong>offsetLeft</strong> of a component. </p>
  
  <pre><code>componentDidMount(){
          var tesNo =ReactDOM.findDOMNode(this.refs.dropDown.refs.input.offsetLeft)
  
      }
  &lt;ReactAutocomplete
      ref="dropDown"
     /*.......*/
  /&gt;
  </code></pre>
  
  <p>While debugging I get the value of the variable <em>tesNo</em> .After that I am getting this error:</p>
  
  <p><em>Consider adding an error boundary to your tree to customize error handling behavior.
  Visit <a href="https://reactjs.org/docs/error-boundaries.html" rel="noreferrer">this site</a> to learn more about error boundaries.
  Invariant Violation: Argument appears to not be a ReactComponent</em></p>
  
  <p>How to solve this error?</p>