From 8f5349eaa141e08b557b16080ea02e568fee9858 Mon Sep 17 00:00:00 2001
From: Guo Xiang Tan <tgx_world@hotmail.com>
Date: Tue, 6 Mar 2018 21:37:38 +0800
Subject: [PATCH] FIX: Only unsubscribe channel if it was subscribed.

---
 .../javascripts/discourse/controllers/user-topics-list.js.es6  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/app/assets/javascripts/discourse/controllers/user-topics-list.js.es6 b/app/assets/javascripts/discourse/controllers/user-topics-list.js.es6
index 956557c14ea..9f877a1bb38 100644
--- a/app/assets/javascripts/discourse/controllers/user-topics-list.js.es6
+++ b/app/assets/javascripts/discourse/controllers/user-topics-list.js.es6
@@ -31,7 +31,8 @@ export default Ember.Controller.extend({
   },
 
   unsubscribe() {
-    this.messageBus.unsubscribe(this.get('channel'));
+    const channel = this.get('channel');
+    if (channel) this.messageBus.unsubscribe(channel);
     this._resetTracking();
     this.set('channel', null);
   },