From 5c9ffd9af5a080acfedc1699f7973edb2622067c Mon Sep 17 00:00:00 2001
From: gorhill <rhill@raymondhill.net>
Date: Mon, 24 Apr 2017 18:30:06 -0400
Subject: [PATCH] fix #2558

---
 platform/firefox/vapi-background.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index 4885528a0..f9d5fd253 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -967,6 +967,8 @@ vAPI.tabs.open = function(details) {
 
         for ( tab of this.getAll() ) {
             var browser = tabWatcher.browserFromTarget(tab);
+            // https://github.com/gorhill/uBlock/issues/2558
+            if ( browser === null ) { continue; }
 
             // Or simply .equals if we care about the fragment
             if ( URI.equalsExceptRef(browser.currentURI) === false ) {