The code

``` javascript
class Comp extends React.Component {
  componentWillMount() {
    setTimeout(() => {
      this.setState({});
    });
  }

  render() {
    return <div onClick={() => {}} />;
  }
}

ReactDOMServer.renderToString(<Comp />);
```

produces errors:

> Warning: React can't find the root component node for data-reactid value `.0`. If you're seeing this message, it probably means that you've loaded two copies of React on the page. At this time, only a single copy of React can be loaded at a time.
> 
> Uncaught TypeError: Cannot read property 'firstChild' of undefined

But if I remove `onClick` handler the errors go away...

See demo: http://codepen.io/dened/pen/YyByYr

spyOn(console, 'error');
      instance = ReactDOM.render(<TestComponent name="y" />, element);
      expect(mountCount).toEqual(4);
      expect(console.error.calls.count()).toBe(1);
      expect(element.innerHTML.length > 0).toBe(true);
      expect(element.innerHTML).not.toEqual(lastMarkup);
      
      expect(numClicks).toEqual(1);
      ReactTestUtils.Simulate.click(ReactDOM.findDOMNode(instance.refs.span));
      expect(numClicks).toEqual(2);
    });
    it('should throw with silly args', function() {
      expect(
        ReactServerRendering.renderToString.bind(
          ReactServerRendering,
          'not a component'
        )
      ).toThrowError(
        'renderToString(): You must pass a valid ReactElement.'
      );
    });
  });
  describe('renderToStaticMarkup', function() {
    it('should not put checksum and React ID on components', function() {
      var NestedComponent = React.createClass({
        render: function() {
          return <div>inner text</div>;
        },
      });
      var TestComponent = React.createClass({