[frogr] Added missing null check (previously removed by mistake)

[Mario Sanchez Prada <msanchez src gnome org>]

commit bebe1c1825324139c68a55e8f41e82be580174b9
Author: Mario Sanchez Prada <msanchez gnome org>
Date:   Fri Nov 2 09:43:10 2012 +0100

    Added missing null check (previously removed by mistake)

 src/frogr-controller.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/frogr-controller.c b/src/frogr-controller.c
index a493401..6fe4a5b 100644
--- a/src/frogr-controller.c
+++ b/src/frogr-controller.c
@@ -379,7 +379,7 @@ _handle_flicksoup_error (FrogrController *self, GError *error, gboolean notify_u
       msg = g_strdup_printf (_("An error happened: %s."), error->message);
     }
 
-  if (notify_user)
+  if (notify_user && error_function)
     {
       GtkWindow *window = NULL;
       window = frogr_main_view_get_window (priv->mainview);