From 3b4a00ce464bd431dd9222c976fd1010735d96c6 Mon Sep 17 00:00:00 2001
From: Tim Mickel <tim.mickel@gmail.com>
Date: Tue, 7 Jun 2016 11:29:51 -0400
Subject: [PATCH] Add check for null `substackNum`, fix numbering

---
 src/engine/blocks.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/engine/blocks.js b/src/engine/blocks.js
index ad4c8d1c7..896e9c8b4 100644
--- a/src/engine/blocks.js
+++ b/src/engine/blocks.js
@@ -56,9 +56,10 @@
  Blocks.prototype.getSubstack = function (id, substackNum) {
      var block = this._blocks[id];
      if (typeof block === 'undefined') return null;
+     if (!substackNum) substackNum = 1;
 
      var inputName = 'SUBSTACK';
-     if (substackNum > 0) {
+     if (substackNum > 1) {
          inputName += substackNum;
      }