Status Code on error
I would like to return an error status code in `onError` handler. What I'm doing now is this:

```php
public function onError(ConnectionInterface $c, \Exception $e) {
	if($c instanceof WsConnection) {
		$c->close(Frame::CLOSE_SRV_ERR);
	} else {
		$c->close();
	}
}
```

Given that `ConnectionInterface` doesn't have a param for status, I need to check for implementation before sending the server error status code 1011. Is this the expected way to do this? 