Comment 1 for bug 1082516

Looks like the problem is coming from configuration #5 in test-gtk-label.json, specifically this entry:

 > {"id": 89,
 > "type": "standard",
 > "icon-name": "blank-icon",
 > "label": "blank"}

"blank-icon" is the magic string used by DBUSMENU_MENUITEM_ICON_NAME_BLANK, which in libdbusmenu-gtk/client.c is processed by image_property_handle() to give the menuitem a blank GtkImage.

In a subsequent call to image_property_handle() we call gtk_image_get_icon_name() on the existing image iff its storage type is GTK_IMAGE_ICON_NAME or GTK_IMAGE_EMPTY. This is legal use of that gtk function, but in the case listed above, the name that's returned is NULL, so we need to test for that before using icon_name elsewhere in image_property_handle().