commit d04ae5a7c24fdc78a7f86cde60b732f518f20a23
Author: Robert Ancell <robert.ancell@canonical.com>
Date:   Thu Nov 3 14:51:43 2022 +0100

    WIP

diff --git a/gtk/gtkcssiconthemevalue.c b/gtk/gtkcssiconthemevalue.c
index e6633c589a..fbbcb34d5e 100644
--- a/gtk/gtkcssiconthemevalue.c
+++ b/gtk/gtkcssiconthemevalue.c
@@ -76,12 +76,16 @@ gtk_css_value_icon_theme_compute (GtkCssValue             *icon_theme,
                                   GtkCssStyle             *style,
                                   GtkCssStyle             *parent_style)
 {
-  GtkIconTheme *icontheme;
+  GtkIconTheme *icontheme = NULL;
 
   if (icon_theme->icontheme)
     icontheme = icon_theme->icontheme;
   else
-    icontheme = gtk_icon_theme_get_for_screen (_gtk_settings_get_screen (_gtk_style_provider_private_get_settings (provider)));
+    {
+      GtkSettings *settings = _gtk_style_provider_private_get_settings (provider);
+      if (settings != NULL)
+        icontheme = gtk_icon_theme_get_for_screen (_gtk_settings_get_screen (settings));
+    }
 
   return gtk_css_icon_theme_value_new (icontheme);
 }
diff --git a/gtk/gtkiconhelper.c b/gtk/gtkiconhelper.c
index f6e3e2956a..461398647e 100644
--- a/gtk/gtkiconhelper.c
+++ b/gtk/gtkiconhelper.c
@@ -489,10 +489,8 @@ ensure_surface_for_gicon (GtkIconHelper    *self,
                                               width,
                                               flags | GTK_ICON_LOOKUP_USE_BUILTIN | GTK_ICON_LOOKUP_GENERIC_FALLBACK,
                                               &error);
-      /* We include this image as resource, so we always have it available or
-       * the icontheme code is broken */
-      g_assert_no_error (error);
-      g_assert (destination);
+      if (destination == NULL)
+        destination = gdk_pixbuf_new(GDK_COLORSPACE_RGB, TRUE, 8, width, height);
       symbolic = FALSE;
     }
 
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 8df1c8e861..201e447d2d 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -4475,6 +4475,8 @@ icon_list_from_theme (GtkWindow   *window,
   icon_theme = gtk_css_icon_theme_value_get_icon_theme
     (_gtk_style_context_peek_property (gtk_widget_get_style_context (GTK_WIDGET (window)),
                                        GTK_CSS_PROPERTY_ICON_THEME));
+  if (icon_theme == NULL)
+    return NULL;
 
   sizes = gtk_icon_theme_get_icon_sizes (icon_theme, name);