add:  if (blankTabToRemove) tabbrowser.removeTab(blankTabToRemove); 
context: function undoCloseTab(aIndex) {  var ss = Cc["@mozilla.org/browser/sessionstore;1"].           getService(Ci.nsISessionStore);  if (ss.getClosedTabCount(window) == 0)    return;  ss.undoCloseTab(window, aIndex || 0);}
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/1cc670df177f6cdf502b2a97ac97a8917f494e8e/browser.js/buggy/browser/base/content/browser.js