add: if (!tableElement) { return; } 
context: EchoTable.disposeCellListeners = function(tableElementId) {    var tableElement = document.getElementById(tableElementId);    for (var rowIndex = 0; rowIndex < tableElement.rows.length; ++rowIndex) {        for (var cellIndex = 0; cellIndex < tableElement.rows[rowIndex].cells.length; ++cellIndex) {            var tdElement = tableElement.rows[rowIndex].cells[cellIndex];            EchoEventProcessor.removeHandler(tdElement.id, "click");            EchoEventProcessor.removeHandler(tdElement.id, "mouseover");            EchoEventProcessor.removeHandler(tdElement.id, "mouseout");        }    }};
meta: 498	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/498/e763c8de8f0af27a7fe6eee2897ff933247af260/Table.js/buggy/src/webcontainer/java/nextapp/echo2/webcontainer/resource/js/Table.js