[gnome-control-center/gnome-3-6] printers: Don't crash without system-config-printer

[Marek Kašík <mkasik src gnome org>]

commit 5a654556de7a85414e9ef3a465f383b9ea4357e7
Author: Marek Kasik <mkasik redhat com>
Date:   Wed Apr 24 13:03:22 2013 +0200

    printers: Don't crash without system-config-printer
    
    Fix error handling in addition of new printer.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=698642

 panels/printers/pp-new-printer.c |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)
---
diff --git a/panels/printers/pp-new-printer.c b/panels/printers/pp-new-printer.c
index 038a2ad..c76f1ac 100644
--- a/panels/printers/pp-new-printer.c
+++ b/panels/printers/pp-new-printer.c
@@ -683,6 +683,7 @@ printer_add_async_scb (GObject      *source_object,
   GDBusConnection     *bus;
   GVariantBuilder      array_builder;
   GVariant            *output;
+  gboolean             cancelled = FALSE;
   PPDName             *ppd_item = NULL;
   GError              *error = NULL;
 
@@ -698,15 +699,15 @@ printer_add_async_scb (GObject      *source_object,
     }
   else
     {
-      if (error->domain != G_IO_ERROR ||
-          error->code != G_IO_ERROR_CANCELLED)
+      cancelled = g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED);
+
+      if (!cancelled)
         g_warning ("%s", error->message);
-      g_error_free (error);
+
+      g_clear_error (&error);
     }
 
-  if (!error ||
-      error->domain != G_IO_ERROR ||
-      error->code != G_IO_ERROR_CANCELLED)
+  if (!cancelled)
     {
       if (ppd_item == NULL || ppd_item->ppd_match_level < PPD_EXACT_MATCH)
         {