title: React defaultProps not working
body: <p>I'm probably doing something stupid, but I can't get defaultProps to work.</p>
  
  <pre><code>export default class MyClass extends Component{
    static propTypes = {
      name: React.PropTypes.string.isRequired,
      field: React.PropTypes.object.isRequired
    }
  
    static defaultProps = {
      field: { value: '', errors: [] }
    }
  
    render() {
      // blah blah
    }
  }
  </code></pre>
  
  <p>I have code that relies on <code>this.props.field.value</code> and <code>this.props.field.errors.length</code> and all my tests are blowing up with <code>TypeError: 'undefined' is not an object (evaluating 'this.props.field.errors.length')</code>, shouldn't my default props give it a default value? Initially, my <code>field</code> prop is an empty object.</p>