/roles api returns an incorrect global property

[juliusxyg]

If you /set-admin first, and /remove-admin, then when you call /roles with that user id, you will get respone like {"status_code": 200, "data": {"5000724": {"channel": {}, "room": {}, "global": [""]}}} .

The global property is not an empty array, which contains an empty string element.