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

var publicInstance = this._instance;
  if (this._debugID !== 0) {
    ReactInstrumentation.debugTool.onBeginLifeCycleTimer(
      this._debugID,
      'componentDidMount'
    );
  }
  publicInstance.componentDidMount();
  if (this._debugID !== 0) {
    ReactInstrumentation.debugTool.onEndLifeCycleTimer(
      this._debugID,
      'componentDidMount'
    );
  }
}
function invokeComponentDidUpdateWithTimer(prevProps, prevState, prevContext) {