From a9aabd637f4af56e0650f948afd02d31864810b8 Mon Sep 17 00:00:00 2001
From: Andrew n marshall <Anm@anm.me>
Date: Fri, 24 Feb 2017 15:41:56 -0800
Subject: [PATCH] Adding warning on duplicate JSON block definition.

---
 core/blockly.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/core/blockly.js b/core/blockly.js
index 558c72014..aeddf97b3 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -410,6 +410,10 @@ Blockly.defineBlocksWithJsonArray = function(jsonArray) {
       console.warn('Block definition #' + i +
         ' in JSON array is missing a type attribute. Skipping.');
     } else {
+      if (Blockly.Blocks[typename]) {
+        console.warn('Block definition #' + i +
+          ' in JSON array overwrites prior definition of "' + typename + '"');
+      }
       Blockly.Blocks[typename] = {
         init: Blockly.jsonInitFactory_(elem)
       };