[gnome-desktop] thumbnail: Print debug if there's no thumbnailer

[Bastien Nocera <hadess src gnome org>]

commit 3d0d7575218f8e03f75e80c50f1f0ad34d6b9d3b
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Jan 16 16:35:58 2018 +0100

    thumbnail: Print debug if there's no thumbnailer
    
    Makes it easier to see whether the problem comes from this particular
    problem or not.

 libgnome-desktop/gnome-desktop-thumbnail.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/libgnome-desktop/gnome-desktop-thumbnail.c b/libgnome-desktop/gnome-desktop-thumbnail.c
index 65ecdbe..c16617b 100644
--- a/libgnome-desktop/gnome-desktop-thumbnail.c
+++ b/libgnome-desktop/gnome-desktop-thumbnail.c
@@ -1089,6 +1089,11 @@ gnome_desktop_thumbnail_factory_generate_thumbnail (GnomeDesktopThumbnailFactory
           g_clear_error (&error);
         }
     }
+  else
+    {
+      g_debug ("Could not find thumbnailer for mime-type '%s'",
+               mime_type);
+    }
 
   g_free (script);