#0  0x00007f327acac267 in g_type_check_instance_cast (type_instance=type_instance@entry=0x2cffb30, iface_type=48411616) at /build/buildd/glib2.0-2.39.4/./gobject/gtype.c:4003
  [Error: /build/buildd/glib2.0-2.39.4/./gobject/gtype.c was not found in source tree]
#1  0x00007f3259a824a5 in picture_scaled (source_object=0x7f324001c790, res=0x33a1810, user_data=0x2cffb30) at bg-pictures-source.c:135
  130: static void
  131: picture_scaled (GObject *source_object,
  132:                 GAsyncResult *res,
  133:                 gpointer user_data)
  134: {
  135:   BgPicturesSource *bg_source = BG_PICTURES_SOURCE (user_data);
  136:   CcAppearanceItem *item;
  137:   GError *error = NULL;
  138:   GdkPixbuf *pixbuf;
  139:   const char *source_url;
  140: 
#2  0x00007f327b3b8b8b in g_task_return_now (task=0x33a1810) at /build/buildd/glib2.0-2.39.4/./gio/gtask.c:1081
  [Error: /build/buildd/glib2.0-2.39.4/./gio/gtask.c was not found in source tree]
#3  0x00007f327b3b8ba9 in complete_in_idle_cb (task=0x33a1810) at /build/buildd/glib2.0-2.39.4/./gio/gtask.c:1090
  [Error: /build/buildd/glib2.0-2.39.4/./gio/gtask.c was not found in source tree]
#4  0x00007f327a9c0a65 in g_main_dispatch (context=0x10a9fa0) at /build/buildd/glib2.0-2.39.4/./glib/gmain.c:3065
  [Error: /build/buildd/glib2.0-2.39.4/./glib/gmain.c was not found in source tree]
#5  g_main_context_dispatch (context=context@entry=0x10a9fa0) at /build/buildd/glib2.0-2.39.4/./glib/gmain.c:3640
  [Error: /build/buildd/glib2.0-2.39.4/./glib/gmain.c was not found in source tree]
#6  0x00007f327a9c0dc8 in g_main_context_iterate (context=context@entry=0x10a9fa0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/buildd/glib2.0-2.39.4/./glib/gmain.c:3711
  [Error: /build/buildd/glib2.0-2.39.4/./glib/gmain.c was not found in source tree]
#7  0x00007f327a9c0e6c in g_main_context_iteration (context=0x10a9fa0, context@entry=0x0, may_block=may_block@entry=1) at /build/buildd/glib2.0-2.39.4/./glib/gmain.c:3772
  [Error: /build/buildd/glib2.0-2.39.4/./glib/gmain.c was not found in source tree]
#8  0x00007f327b3da97c in g_application_run (application=0x2a4f830, argc=argc@entry=1, argv=argv@entry=0x7fff92cca8a8) at /build/buildd/glib2.0-2.39.4/./gio/gapplication.c:1695
  [Error: /build/buildd/glib2.0-2.39.4/./gio/gapplication.c was not found in source tree]
#9  0x00000000004071d2 in main (argc=1, argv=0x7fff92cca8a8) at control-center.c:336
  331:   g_signal_connect (application, "startup",
  332:                     G_CALLBACK (application_startup_cb), shell);
  333:   g_signal_connect (application, "command-line",
  334:                     G_CALLBACK (application_command_line_cb), shell);
  335: 
  336:   status = g_application_run (G_APPLICATION (application), argc, argv);
  337: 
  338:   g_object_unref (application);
  339: 
  340:   return status;
  341: }