Don’t read only a single line, read all of the response. The response may have multiple lines, like in this case, it does:
$ curl http://tmi.twitch.tv/group/user/notventic/chatters
{
"_links": {},
"chatter_count": 0,
"chatters": {
"moderators": [],
"staff": [],
"admins": [],
"global_mods": [],
"viewers": []
}
}