Handle NULL objects in json_object_get_userdata() by returning NULL, but abort in json_object_set_userdata() since we can't actually do anything with the userdata.
Handle NULL objects in json_object_get_userdata() by returning NULL, but abort in json_object_set_userdata() since we can't actually do anything with the userdata.

Nzbuu/json-c,Nzbuu/json-c,Nzbuu/json-c,Nzbuu/json-c