[gnome-music/wip/mschraal/async-queue: 19/25] artstack: Add missing init declaration

[Marinus Schraal <mschraal src gnome org>]

commit 916c05336ca5850e0cac55c97183b8f06a090d6b
Author: Marinus Schraal <mschraal gnome org>
Date:   Sun Aug 15 01:11:42 2021 +0200

    artstack: Add missing init declaration

 gnomemusic/widgets/artstack.py | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gnomemusic/widgets/artstack.py b/gnomemusic/widgets/artstack.py
index 9a6a87c46..5e7014d3f 100644
--- a/gnomemusic/widgets/artstack.py
+++ b/gnomemusic/widgets/artstack.py
@@ -46,6 +46,7 @@ class ArtStack(Gtk.Stack):
         super().__init__()
 
         self._cache = ArtCache()
+        self._coreobject = None
         self._handler_id = 0
         self._size = size
         self._thumbnail_id = 0