From 9860239ea3cf5b30e9468f1b453891ebc576ef24 Mon Sep 17 00:00:00 2001
From: janekptacijarabaci <janekptacijarabaci@seznam.cz>
Date: Sun, 13 May 2018 08:28:44 +0200
Subject: [PATCH] about:sessionrestore - fix an error "treeView.treeBox is
 null" in aboutSessionRestore.js

---
 browser/components/sessionstore/content/aboutSessionRestore.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/browser/components/sessionstore/content/aboutSessionRestore.js b/browser/components/sessionstore/content/aboutSessionRestore.js
index 8a9410aa8f..165f480411 100644
--- a/browser/components/sessionstore/content/aboutSessionRestore.js
+++ b/browser/components/sessionstore/content/aboutSessionRestore.js
@@ -188,6 +188,9 @@ function onListClick(aEvent) {
   if (aEvent.button == 2)
     return;
 
+  if (!treeView.treeBox) {
+    return;
+  }
   var cell = treeView.treeBox.getCellAt(aEvent.clientX, aEvent.clientY);
   if (cell.col) {
     // Restore this specific tab in the same window for middle/double/accel clicking