[gnome-music/wip/mschraal/rework-art-widget: 14/26] artstack: On dark mode only update placeholder

[Marinus Schraal <mschraal src gnome org>]

commit e1fc65c9743e4aa2d43ecefe906f4f920c3dda10
Author: Marinus Schraal <mschraal gnome org>
Date:   Fri Mar 18 10:19:54 2022 +0100

    artstack: On dark mode only update placeholder

 gnomemusic/widgets/artstack.py | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gnomemusic/widgets/artstack.py b/gnomemusic/widgets/artstack.py
index 1b12f8a7b..643247be2 100644
--- a/gnomemusic/widgets/artstack.py
+++ b/gnomemusic/widgets/artstack.py
@@ -153,6 +153,12 @@ class ArtStack(Gtk.Stack):
     def _on_dark_changed(
             self, style_manager: Adw.StyleManager,
             pspec: GObject.ParamSpecBoolean) -> None:
+        if self._coreobject is None:
+            return
+
+        if self._coreobject.props.thumbnail != "generic":
+            return
+
         default_icon = DefaultIcon(self).get(self._art_type, self._size)
 
         self._cover.props.paintable = default_icon