Possibly websocket heartbeat causing json warnings

[CptPie]

As reported by aze in discord:

Only oddity was the logs doing this quite a bit throughout:

[INFO] 2023/01/24 03:05:56 [handler] Could not unmarshal join data "": unexpected end of JSON input
[INFO] 2023/01/24 03:06:41 [handler] Could not unmarshal join data "": unexpected end of JSON input
[INFO] 2023/01/24 03:07:26 [handler] Could not unmarshal join data "": unexpected end of JSON input

couple hundred of those over the course of 2.5 hours

From a limited amount of digging my working theory is that the heartbeat for the websockets might not send valid json "{}" and instead sends "" which causes the mentioned error.