From c0956b20b90e5b57ead30c783c5b102408a1190a Mon Sep 17 00:00:00 2001
From: hackademix
Date: Thu, 27 Dec 2018 10:53:53 +0100
Subject: Safer cookie-less check for unrestricted tabs from subdocuments.

---
 src/content/staticNS.js | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/content/staticNS.js b/src/content/staticNS.js
index 0cd254c..e169087 100644
--- a/src/content/staticNS.js
+++ b/src/content/staticNS.js
@@ -70,10 +70,15 @@
           // or the cookie might have been deleted in a race condition,
           // so here we try to check the parent
           let checkParent = parent.wrappedJSObject.checkNoScriptUnrestricted;
-          if (checkParent) {
-            let challenge = uuid();
-            let unrestricted = checkParent(challenge) === checkUnrestricted(challenge);
-            this.config.tabInfo = {unrestricted, inherited: true};
+          if (typeof checkParent  === "function") {
+            try {
+              let challenge = uuid();
+              let unrestricted = checkParent(challenge) === checkUnrestricted(challenge);
+              this.config.tabInfo = {unrestricted, inherited: true};
+            } catch (e) {
+              debug("Exception thrown while checking parent unrestricted tab marker. Something fishy going on...")
+              error(e);
+            }
           }
         }
       }
-- 
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