From 26ea42c2641084fc5312e810f9df1a8ac28faec6 Mon Sep 17 00:00:00 2001
From: "duzc2dtw@gmail.com" <duzc2dtw@gmail.com>
Date: Sat, 9 Dec 2017 20:41:43 +0800
Subject: [PATCH] #1376

---
 core/extensions.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/core/extensions.js b/core/extensions.js
index 1ce582cc1..c32e1d60f 100644
--- a/core/extensions.js
+++ b/core/extensions.js
@@ -74,6 +74,9 @@ Blockly.Extensions.register = function(name, initFn) {
  *     registered.
  */
 Blockly.Extensions.registerMixin = function(name, mixinObj) {
+  if(!goog.isObject(mixinObj)){
+    throw new Error('Error: Mixin "' + name + '" must be a object');
+  }
   Blockly.Extensions.register(name, function() {
     this.mixin(mixinObj);
   });