The status as JSON (the mint result's AvatarStatusJson), or nothing.
The status; null when there is none, the JSON is malformed, or a field is missing or of the wrong type (a
reason that isn't text included). A reason this version does not know, such as a newer server's, is left out and the
status marked ReasonUnknown.
Reads a RealtimeAvatarStatus from its JSON string.