rem: if (link) { link = link.QueryInterface(Components.interfaces.nsIRDFLiteral); 
add: if (link instanceof Components.interfaces.nsIRDFLiteral && link.Value) 
context: function onselect_loadURI(tree) {    try {        var resource = tree.view.getResourceAtIndex(tree.currentIndex);	var link = tree.database.GetTarget(resource, NC_LINK, true);	if (link) {            link = link.QueryInterface(Components.interfaces.nsIRDFLiteral);            loadURI(link.Value);        }    } catch (e) {    }// when switching between tabs a spurious row number is returned.}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/e877c267f4ca2e54c05bb6b6328ad735e98d9c17/help.js/clean/toolkit/components/help/content/help.js