on line 4691 there is :

4688: event.data = handleObj.data;
4689: event.handleObj = handleObj;
4690: 
4691: ret = ( (jQuery.event.special[ handleObj.origType ] || {}).handle || handleObj.handler )
4692:     .apply( matched.elem, args );

In this line there is no check if handler exists. My solution to that is:

4688: event.data = handleObj.data;
4689: event.handleObj = handleObj;
4690:
4691: var tmp_handler = ( (jQuery.event.special[ handleObj.origType ] || {}).handle || handleObj.handler );
4692: if (typeof tmp_handler === 'function') {
4693:   ret = tmp_handler.apply( matched.elem, args );
4694: }

I noticed this in version 1.7.2 but it exists in all version up to date.