Bug 1634414 - Check principal before using IsThirdPartyPrincipal in AllowAccessFor r=timhuang

Differential Revision: https://phabricator.services.mozilla.com/D73418

toolkit/components/antitracking/ContentBlocking.cpp

@@ -322,6 +322,10 @@ ContentBlocking::AllowAccessFor(
       bool isThirdParty;
       nsCOMPtr<nsIPrincipal> principal =
           AntiTrackingUtils::GetPrincipal(aParentContext);
+      if (!principal) {
+        LOG(("Can't get the principal from the browsing context"));
+        return StorageAccessGrantPromise::CreateAndReject(false, __func__);
+      }
       Unused << trackingPrincipal->IsThirdPartyPrincipal(principal,
                                                          &isThirdParty);
       runInSameProcess = !isThirdParty;