Websocket error message not documented

[hi94740]

{
  "err": "authToken doesn't correspond with an active session",
  "authToken": "authcookie_xxx",
  "ip": "xxx.xxx.xxx.xxx"
}

I got this message when I connected from a different IP than the one I used to get Cookie. The connection was closed immediately after this message.

[binn]

Authcookies only work from the IP it was granted to.

[hi94740]

Authcookies only work from the IP it was granted to.

Yeah that is apparently what this error message is for.
I just think this should be added to the documentation.
Websocket documentation does not include any error message currently.