rem: contextItem.hidden = contextSep.hidden = !(culprit && culprit.href.match(/\.user\.js(\?|$)/i) != null); 
add: contextItem.hidden = contextSep.hidden = !(culprit && culprit.href && culprit.href.match(/\.user\.js(\?|$)/i) != null); 
context: GM_BrowserUI.contextMenuShowing = function() {  GM_log('> contextMenuShowing');  var contextItem = ge("install-userscript");  var contextSep = ge("install-userscript-sep");  var culprit = document.popupNode;  while (culprit && culprit.tagName.toLowerCase() != "a") {     culprit = culprit.parentNode;  }  contextItem.hidden =     contextSep.hidden =     !(culprit && culprit.href.match(/\.user\.js(\?|$)/i) != null);  GM_log('< contextMenuShowing');}
meta: 4585	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/4585/89e156ed0e53a82c2bbb6c96f99885a6d80d34aa/browser.js/buggy/src/content/browser.js