[totem] backend: Fix warning if the vis plugin doesn't exist

[Bastien Nocera <hadess src gnome org>]

commit 483255f61b26ee26362d8f4a202f2458b133578d
Author: Bastien Nocera <hadess hadess net>
Date:   Sat Jul 14 23:25:33 2012 +0100

    backend: Fix warning if the vis plugin doesn't exist

 src/backend/bacon-video-widget.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/backend/bacon-video-widget.c b/src/backend/bacon-video-widget.c
index b2696ce..7eb7354 100644
--- a/src/backend/bacon-video-widget.c
+++ b/src/backend/bacon-video-widget.c
@@ -4437,7 +4437,11 @@ setup_vis_find_factory (BaconVideoWidget * bvw, const gchar * vis_name)
   const char *factory_name;
 
   ensure_vis_plugins_list (bvw);
+
   factory_name = g_hash_table_lookup (bvw->priv->vis_plugins_ht, vis_name);
+  if (factory_name == NULL)
+    return NULL;
+
   return gst_element_factory_find (factory_name);
 }