1 files changed, 2 insertions, 3 deletions
diff --git a/js/codeq/prolog.js b/js/codeq/prolog.js
index 1b8d3c3..18e3fdd 100644
--- a/js/codeq/prolog.js
+++ b/js/codeq/prolog.js
@@ -47,8 +47,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>. */
                 .fail(function (reason) {
                     codeq.log.error('Failed to obtain the problem definition: ' + reason, reason);
                     alert('Failed to obtain the problem definition: ' + reason);
-
-                    history.back();//TODO test
+                    history.back();
                 })
                 .done();
         },
@@ -59,7 +58,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>. */
             // end of experiment: Prolog hints
 
             jqScreen.css('display', 'none');
-            prologHandler.destroy();
+            if (prologHandler) prologHandler.destroy();
             prologHandler = null;
 
             $('#navigation-problem-list').css('display', 'none');