If the connection is broken, there is no response to this function:

* Create an event from a response object
* @param {Object} response The XHR response object
* @return {Ext.direct.Event} The event
createEvent: function(response) {
return Ext.create('direct.' + response.type, response);
Since response is undefined, trying to get response.type throws an error that is never caught.

This is in ST2 as well.