[gimp] app: add back needed NULL checks

[Mikael Magnusson <mikachu src gnome org>]

commit 6cb9ef6e383026fecb86311e947e55e10b77c8f9
Author: Mikael Magnusson <mikachu src gnome org>
Date:   Sun Jun 16 19:58:47 2013 +0200

    app: add back needed NULL checks

 app/dialogs/file-save-dialog.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/app/dialogs/file-save-dialog.c b/app/dialogs/file-save-dialog.c
index b7f5595..762b00b 100644
--- a/app/dialogs/file-save-dialog.c
+++ b/app/dialogs/file-save-dialog.c
@@ -229,10 +229,12 @@ file_save_dialog_response (GtkWidget *save_dialog,
       g_free (uri);
       g_free (basename);
 
-      gimp_file_dialog_set_sensitive (dialog, TRUE);
+      if (dialog)
+        gimp_file_dialog_set_sensitive (dialog, TRUE);
     }
 
-  g_signal_handler_disconnect (dialog, handler_id);
+  if (dialog)
+    g_signal_handler_disconnect (dialog, handler_id);
 }
 
 /*