From 38e42cf71e07b9c96f95adbc2e7c1ea34dd92035 Mon Sep 17 00:00:00 2001
From: Michael Teeuw <michael@xonaymedia.nl>
Date: Thu, 31 Mar 2016 19:25:53 +0200
Subject: [PATCH] Type check.

---
 js/main.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/js/main.js b/js/main.js
index 667afcc8..fb1411e9 100644
--- a/js/main.js
+++ b/js/main.js
@@ -414,7 +414,7 @@ var MM = (function() {
 		hideModule: function(module, speed, callback) {
 			hideModule(module, speed, function() {
 				module.hidden = true;
-				callback();
+				if (typeof callback === 'function') { callback(); }	
 			});
 		},