Index: lams_central/web/includes/javascript/groupDisplay.js
===================================================================
diff -u -r6ad3d1341b3dc1f066c69c7129a8c1dff15980a5 -rf0e4de72f0144cb9ac7e8bc07fe53cbcf1d248cb
--- lams_central/web/includes/javascript/groupDisplay.js	(.../groupDisplay.js)	(revision 6ad3d1341b3dc1f066c69c7129a8c1dff15980a5)
+++ lams_central/web/includes/javascript/groupDisplay.js	(.../groupDisplay.js)	(revision f0e4de72f0144cb9ac7e8bc07fe53cbcf1d248cb)
@@ -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;