From b8013704cffbdedd2f82bcf38a556c6a74754615 Mon Sep 17 00:00:00 2001
From: Daniel van Vugt <daniel.van.vugt@canonical.com>
Date: Tue, 14 Mar 2023 17:35:34 +0800
Subject: [PATCH] appDisplay: Avoid using an undefined _swipeTracker

It might have been deleted already during shutdown by `_onDestroy()`.

Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6512
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2693>
---
 js/ui/appDisplay.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index 17afb899d..75a458f7b 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -1237,7 +1237,8 @@ var BaseAppView = GObject.registerClass({
     }
 
     vfunc_unmap() {
-        this._swipeTracker.enabled = false;
+        if (this._swipeTracker)
+            this._swipeTracker.enabled = false;
         this._disconnectDnD();
         super.vfunc_unmap();
     }