Hello,

After updating to React 15.0.1, we are getting the following error:

```
Uncaught TypeError: Cannot read property 'addEventListener' of null
```

![image](https://cloud.githubusercontent.com/assets/4996164/14602577/5bb4e9f2-0571-11e6-9aa1-98de49f50d76.png)

var inst = this._instance;
    if (inst.componentWillUnmount && !inst._calledComponentWillUnmount) {
      inst._calledComponentWillUnmount = true;
      if (__DEV__) {
        if (this._debugID !== 0) {
          ReactInstrumentation.debugTool.onBeginLifeCycleTimer(
            this._debugID,
            'componentWillUnmount'
          );
        }
      }
      if (safely) {
        var name = this.getName() + '.componentWillUnmount()';
        ReactErrorUtils.invokeGuardedCallback(name, inst.componentWillUnmount.bind(inst));
      } else {
        inst.componentWillUnmount();
      }
      if (__DEV__) {
        if (this._debugID !== 0) {
          ReactInstrumentation.debugTool.onEndLifeCycleTimer(
            this._debugID,
            'componentWillUnmount'
          );
        }
      }
    }
    if (this._renderedComponent) {
      ReactReconciler.unmountComponent(this._renderedComponent, safely);
      this._renderedNodeType = null;
      this._renderedComponent = null;