From fd36bab1fcd94e4b6611f462eec0dd704977da67 Mon Sep 17 00:00:00 2001
From: Dan Ordille <dan@codecademy.com>
Date: Tue, 2 Jun 2015 16:51:38 -0400
Subject: [PATCH] Fix possible race condition in websocket heartbeat callback

---
 src/trans-websocket.coffee | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/trans-websocket.coffee b/src/trans-websocket.coffee
index 52c137f9..c1b95110 100644
--- a/src/trans-websocket.coffee
+++ b/src/trans-websocket.coffee
@@ -101,7 +101,8 @@ class WebSocketReceiver extends transport.GenericReceiver
             super
 
     heartbeat_timeout: ->
-        @session.close(3000, 'No response from heartbeat')
+        if @session?
+            @session.close(3000, 'No response from heartbeat')