Wikimedia Bugzilla is closed!

For example, query with http://www.wikidata.org/w/api.php?action=wbgetentities&ids=Q43684&languages=zh-cn&format=jsonfm&props=aliases

will get 
{
    "entities": {
        "q43684": {
            "id": "q43684",
            "type": "item",
            "aliases": {
                "zh-cn": [

                ]
            }
        }
    },
    "success": 1
}

data.entities['q43684'].aliases['zh-cn'] = []; 
It is an empty set.

If one enters an alias, then removes it, there could be an empty set left.