From dc8765b590dba17206ebcae8645d0cbb9758c9ee Mon Sep 17 00:00:00 2001
From: Joseph Schorr <jschorr@gmail.com>
Date: Wed, 30 Apr 2014 17:12:42 -0400
Subject: [PATCH] Fix potential NPE in graphing class

---
 static/js/graphing.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/static/js/graphing.js b/static/js/graphing.js
index f74175015..f166de025 100644
--- a/static/js/graphing.js
+++ b/static/js/graphing.js
@@ -197,6 +197,10 @@ ImageHistoryTree.prototype.draw = function(container) {
     .attr("class", "image-tree");
 
   var vis = rootSvg.append("svg:g");
+  if (!vis) {
+    this.container_ = null;
+    return;
+  }
 
   var formatComment = this.formatComment_;
   var formatTime = this.formatTime_;