rem: if (tr) 
add: if (tr && tr.childNodes[1]) 
context: function findPreviousColumnInfo (table){    var extents = new Array();    var tr = table.firstChild.lastChild;    var className = tr ? tr.childNodes[1].getAttribute("class") : "";    while (tr && className.search(/msg-user|msg-type|msg-nested-td/) == -1)    {        extents.push(tr);        tr = tr.previousSibling;        if (tr)            className = tr.childNodes[1].getAttribute("class");    }        if (!tr || className != "msg-user")        return {extents: [], nickColumns: []};        extents.push(tr);    var nickCol = tr.firstChild;    var nickCols = new Array();    while (nickCol)    {        if (nickCol.getAttribute("class") == "msg-user")            nickCols.push (nickCol);        nickCol = nickCol.nextSibling;    }    return {extents: extents, nickColumns: nickCols};}    
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/7e998d1a2e81d56757ccb1d104bf94e8be456a0d/static.js/buggy/extensions/irc/xul/content/static.js