[gnome-menus] libmenu: Fix critical warning when trying to load "" menu

[Vincent Untz <vuntz src gnome org>]

commit c45596c3d87fa3e344b9e9a32c51190e12d67d93
Author: Vincent Untz <vuntz gnome org>
Date:   Thu Jul 21 17:13:18 2011 +0200

    libmenu: Fix critical warning when trying to load "" menu
    
    Yes, this is a weird use of the API, but still.

 libmenu/gmenu-tree.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)
---
diff --git a/libmenu/gmenu-tree.c b/libmenu/gmenu-tree.c
index 9c3fe7e..b4c1f87 100644
--- a/libmenu/gmenu-tree.c
+++ b/libmenu/gmenu-tree.c
@@ -608,11 +608,10 @@ gmenu_tree_load_sync (GMenuTree  *tree,
   if (tree->loaded)
     return TRUE;
 
-  gmenu_tree_build_from_layout (tree, &local_error);
-
-  if (local_error)
+  if (!gmenu_tree_build_from_layout (tree, &local_error))
     {
-      g_propagate_error (error, local_error);
+      if (local_error)
+        g_propagate_error (error, local_error);
       return FALSE;
     }