Cancel if there is no thread

Author: rossjrw

package.json

@@ -1,6 +1,6 @@
 {
   "name": "scpwiki-staff-id",
-  "version": "2.2.0",
+  "version": "2.2.1",
   "description": "A [Tampermonkey](https://chrome.google.com/webstore/detail/tampermonkey/dhdgffkkebhmkfjojejmpbldmpobfkfo) userscript that adds a line of text to forum posts by staff members to show you what position they hold.",
   "main": "scpwiki-staff-ids.user.js",
   "scripts": {

scpwiki-staff-ids.user.js

@@ -17,7 +17,7 @@ select "SCP-Wiki Staff Identification", and click Uninstall.
 // ==UserScript==
 // @name        SCP-Wiki Staff Identification 2
 // @description Shows who's staff and what position they hold
-// @version     v2.2.0
+// @version     v2.2.1
 // @updateURL   https://github.com/scpwiki/SCP-Wiki-Staff-Identification/raw/master/scpwiki-staff-ids.user.js
 // @downloadURL https://github.com/scpwiki/SCP-Wiki-Staff-Identification/raw/master/scpwiki-staff-ids.user.js
 // @include     http://scpwiki.com/forum*
@@ -172,6 +172,7 @@ function setStaffIds() {
   } else {
     container = document.getElementsByClassName("thread-container")[0];
   }
+  if (!container) return;
 
   var infoSpans = container.getElementsByClassName("info");
   var userName = "";