add: if (!selectElement) { continue; } 
context: EchoListComponentDhtml.MessageProcessor.processDispose = function(disposeMessageElement) {    for (var item = disposeMessageElement.firstChild; item; item = item.nextSibling) {        var elementId = item.getAttribute("eid");        var selectElement = document.getElementById(elementId);        var itemElements = selectElement.getElementsByTagName("div");        for (var i = 0; i < itemElements.length; ++i) {            EchoEventProcessor.removeHandler(itemElements[i].id, "click");            EchoEventProcessor.removeHandler(itemElements[i].id, "mouseout");            EchoEventProcessor.removeHandler(itemElements[i].id, "mouseover");        }    }};
meta: 498	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/498/4d0fbc236cc9e250b0588642a818116f4cfb9ffc/ListComponentDhtml.js/buggy/src/webcontainer/java/nextapp/echo2/webcontainer/resource/js/ListComponentDhtml.js