title: React Warning: Failed prop type: Invalid prop of type `Object` supplied
body: <p>I am getting the warning "Warning: Failed prop type: Invalid prop  of type <code>Object</code> supplied to , expected instance of <code>bound checkType</code>."</p>
  
  <p>This is my proptypes:</p>
  
  <pre><code>FieldTable.propTypes = {
      rawData: PropTypes.instanceOf(PropTypes.object).isRequired,
      percentCols: PropTypes.arrayOf(PropTypes.string).isRequired,
      specialColNames: PropTypes.instanceOf(PropTypes.object).isRequired,
      scenarioHeaders: PropTypes.instanceOf(PropTypes.object),
      headerHierarchies: PropTypes.arrayOf(PropTypes.object).isRequired
  };
  </code></pre>
  
  <p>What is this 'bound checkType' it is referring to and how should I be validating my object props to avoid this warning?  The objects themselves are JSON objects received from asynchronous calls, and generated in other components.The rawData object, for example, comes from a component that lets the user upload an excel spreadsheet then parses the spreadsheet into a JSON object.  Don't know if that's useful information or not.</p>
  
  <p>Thanks for any assistance and especially any deeper discussions that may arise from this question.</p>