[gnome-control-center] sound: Fix gtk_tree_model_get_iter_first() retval

[Bastien Nocera <hadess src gnome org>]

commit b410ec353cca6333fcb7b8e40db9c36ac3f69e78
Author: Bastien Nocera <hadess hadess net>
Date:   Tue May 26 13:22:03 2015 +0200

    sound: Fix gtk_tree_model_get_iter_first() retval
    
    https://bugzilla.gnome.org/show_bug.cgi?id=749892

 panels/sound/gvc-sound-theme-chooser.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/panels/sound/gvc-sound-theme-chooser.c b/panels/sound/gvc-sound-theme-chooser.c
index bcf4b0d..4d1ac98 100644
--- a/panels/sound/gvc-sound-theme-chooser.c
+++ b/panels/sound/gvc-sound-theme-chooser.c
@@ -291,7 +291,7 @@ update_alert_model (GvcSoundThemeChooser  *chooser,
         GtkTreeIter   iter;
 
         model = gtk_tree_view_get_model (GTK_TREE_VIEW (chooser->priv->treeview));
-        gtk_tree_model_get_iter_first (model, &iter);
+        g_assert (gtk_tree_model_get_iter_first (model, &iter));
         do {
                 char    *this_id;