[gtk: 1/2] Don't crash when updating the icon on a `GtkScaleButton` with a non-`NULL` empty icon list

[Matthias Clasen <matthiasc src gnome org>]

commit 3f329b2d0f11ff7b30120bed4be0a0fb94d8d178
Author: Sebastian Dröge <sebastian centricular com>
Date:   Sun Feb 13 11:16:32 2022 +0200

    Don't crash when updating the icon on a `GtkScaleButton` with a non-`NULL` empty icon list

 gtk/gtkscalebutton.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkscalebutton.c b/gtk/gtkscalebutton.c
index 2012cf49d2..311ea01192 100644
--- a/gtk/gtkscalebutton.c
+++ b/gtk/gtkscalebutton.c
@@ -884,7 +884,7 @@ gtk_scale_button_update_icon (GtkScaleButton *button)
   const char *name;
   guint num_icons;
 
-  if (!priv->icon_list || priv->icon_list[0][0] == '\0')
+  if (!priv->icon_list || !priv->icon_list[0] || priv->icon_list[0][0] == '\0')
     {
       gtk_button_set_icon_name (GTK_BUTTON (priv->button), "image-missing");
       return;