[gegl] operation: Add a precondition check to gegl_operation_class_set_key ()

[Michael Henning <mhenning src gnome org>]

commit 667da18a7c32ca93dbb55a141b00240d2c862e92
Author: Michael Henning <drawoc darkrefraction com>
Date:   Tue Jul 30 16:54:17 2013 -0400

    operation: Add a precondition check to gegl_operation_class_set_key ()

 gegl/operation/gegl-operation.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gegl/operation/gegl-operation.c b/gegl/operation/gegl-operation.c
index d67ae9a..590eddd 100644
--- a/gegl/operation/gegl-operation.c
+++ b/gegl/operation/gegl-operation.c
@@ -647,6 +647,8 @@ gegl_operation_class_set_key (GeglOperationClass *klass,
 {
   gchar *key_value_dup;
 
+  g_return_if_fail (key_name != NULL);
+
   if (!key_value)
     {
       g_hash_table_remove (klass->keys, key_name);