Index: lams_central/web/includes/javascript/groupDisplay.js
===================================================================
RCS file: /usr/local/cvsroot/lams_central/web/includes/javascript/groupDisplay.js,v
diff -u -r1.37.2.16 -r1.37.2.17
--- lams_central/web/includes/javascript/groupDisplay.js	25 Apr 2016 08:30:43 -0000	1.37.2.16
+++ lams_central/web/includes/javascript/groupDisplay.js	9 May 2016 09:05:10 -0000	1.37.2.17
@@ -507,8 +507,11 @@
 		'title' : 'Authoring',
 		'beforeClose' : function(){
 			// if LD was modified, ask the user if he really wants to exit
-			var canClose = $('iframe', this)[0].contentWindow.GeneralLib.canClose();
-			if (canClose || confirm(LABELS.NAVIGATE_AWAY_CONFIRM)) {
+			var innerLib = $('iframe', this)[0].contentWindow.GeneralLib,
+				// no innerLib means that an exception occured in Authoring
+				// and the interface is not usable anyway
+				canClose = !innerLib || innerLib.canClose() || confirm(LABELS.NAVIGATE_AWAY_CONFIRM);
+			if (canClose) {
 				$('iframe', this).attr('src', null);
 			} else {
 				return false;