From 13e362a1dfe53128a2d95f6653f89e24151a9a97 Mon Sep 17 00:00:00 2001
From: Joseph Schorr <joseph.schorr@coreos.com>
Date: Tue, 24 Feb 2015 13:37:02 -0500
Subject: [PATCH] JS NPE fix

---
 static/js/graphing.js | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/static/js/graphing.js b/static/js/graphing.js
index 18bb09496..60e7d1b33 100644
--- a/static/js/graphing.js
+++ b/static/js/graphing.js
@@ -521,6 +521,11 @@ ImageHistoryTree.prototype.pruneUnreferenced_ = function(node) {
     }
     node.children = surviving_children;
   }
+
+  if (!node.tags) {
+    return node.children.length == 0;
+  }
+
   return (node.children.length == 0 && node.tags.length == 0);
 };