Index: lams_monitoring/web/includes/javascript/monitorLesson.js
===================================================================
diff -u -r3af7e54686064a9b6622d4751d70ea2c89f9abac -r6ea52c47664df489d5d3d64115828c0eef4a1426
--- lams_monitoring/web/includes/javascript/monitorLesson.js	(.../monitorLesson.js)	(revision 3af7e54686064a9b6622d4751d70ea2c89f9abac)
+++ lams_monitoring/web/includes/javascript/monitorLesson.js	(.../monitorLesson.js)	(revision 6ea52c47664df489d5d3d64115828c0eef4a1426)
@@ -1746,6 +1746,10 @@
  * Escapes HTML tags to prevent XSS injection.
  */
 function escapeHtml(unsafe) {
+	if (unsafe == undefined) {
+		return "";
+	}
+	
     return unsafe
         .replace(/&/g, "&")
         .replace(/</g, "&lt;")