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

if (__DEV__) {
      if (this._debugID) {
        var callback = () => ReactInstrumentation.debugTool.onComponentHasUpdated(this._debugID);
        transaction.getReactMountReady().enqueue(callback, this);
      }
    }
  },
  /**
   * Call the component's `render` method and update the DOM accordingly.
   *
   * @param {ReactReconcileTransaction} transaction
   * @internal
   */
  _updateRenderedComponent: function(transaction, context) {
    var prevComponentInstance = this._renderedComponent;
    var prevRenderedElement = prevComponentInstance._currentElement;
    var nextRenderedElement = this._renderValidatedComponent();
    if (shouldUpdateReactComponent(prevRenderedElement, nextRenderedElement)) {
      ReactReconciler.receiveComponent(
        prevComponentInstance,
        nextRenderedElement,
        transaction,
        this._processChildContext(context)
      );
    } else {
      var oldHostNode = ReactReconciler.getHostNode(prevComponentInstance);
      ReactReconciler.unmountComponent(prevComponentInstance, false);
      this._renderedNodeType = ReactNodeTypes.getType(nextRenderedElement);
      var child = this._instantiateReactComponent(
        nextRenderedElement