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 initialState = inst.state;
    if (initialState === undefined) {
      inst.state = initialState = null;
    }
    invariant(
      typeof initialState === 'object' && !Array.isArray(initialState),
      '%s.state: must be set to an object or null',
      this.getName() || 'ReactCompositeComponent'
    );
    this._pendingStateQueue = null;
    this._pendingReplaceState = false;
    this._pendingForceUpdate = false;
    var markup;
    if (inst.unstable_handleError) {
      markup = this.performInitialMountWithErrorHandling(
        renderedElement,
        hostParent,
        hostContainerInfo,
        transaction,
        context
      );
    } else {
      markup = this.performInitialMount(renderedElement, hostParent, hostContainerInfo, transaction, context);
    }
    if (inst.componentDidMount) {
      if (__DEV__) {
        transaction.getReactMountReady().enqueue(invokeComponentDidMountWithTimer, this);
      } else {
        transaction.getReactMountReady().enqueue(inst.componentDidMount, inst);