[gthumb/ext] check for NULL pointer before unreferencing

[Paolo Bacchilega <paobac src gnome org>]

commit 1802fdb9e12bce8b765732981533a94538fb730f
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sat Aug 29 13:29:36 2009 +0200

    check for NULL pointer before unreferencing

 gthumb/gth-main.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/gthumb/gth-main.c b/gthumb/gth-main.c
index 6fa4dee..b177e17 100644
--- a/gthumb/gth-main.c
+++ b/gthumb/gth-main.c
@@ -124,11 +124,14 @@ gth_main_finalize (GObject *object)
 		g_list_foreach (gth_main->priv->metadata_provider, (GFunc) g_object_unref, NULL);
 		g_list_free (gth_main->priv->metadata_provider);
 
-		g_hash_table_unref (gth_main->priv->sort_types);
-		g_hash_table_unref (gth_main->priv->tests);
-		g_hash_table_unref (gth_main->priv->loaders);
-
-		g_hash_table_unref (gth_main->priv->types);
+		if (gth_main->priv->sort_types != NULL)
+			g_hash_table_unref (gth_main->priv->sort_types);
+		if (gth_main->priv->tests != NULL)
+			g_hash_table_unref (gth_main->priv->tests);
+		if (gth_main->priv->loaders != NULL)
+			g_hash_table_unref (gth_main->priv->loaders);
+		if (gth_main->priv->types != NULL)
+			g_hash_table_unref (gth_main->priv->types);
 
 		if (gth_main->priv->bookmarks != NULL)
 			g_bookmark_file_free (gth_main->priv->bookmarks);