Handle WebSocket Closing Error

[LEX0RE]

Fix false ERROR log on intentional WebSocket close

Problem

When Close() is called explicitly on a PsyNetRPC instance, the internal readMessages() goroutine is blocked on wsConn.ReadMessage(). Closing the underlying TCP socket causes ReadMessage() to return a use of closed network connection error, which is then logged as ERROR:

{"level":"ERROR","msg":"failed to read websocket message","err":"read tcp 172.22.0.8:38354->34.149.116.40:443: use of closed network connection"}

This is misleading — the connection was closed intentionally, not due to a real network failure. A common pattern that triggers this is opening a short-lived RPC connection per request:

rpc, _, err := GetRPC(psyNet, player)
if err != nil {
    return err
}
defer rpc.Close() // closes the socket → readMessages logs a false ERROR

profiles, err := rpc.GetProfiles(ctx, playerIDs)

Root cause

readMessages() does not distinguish between an expected closure (triggered by Close()) and an unexpected network error. Both are logged at ERROR level.

Fix

Check the connected flag — which is already set to false by Close() before the socket is closed — to determine whether the error is expected:

if err != nil {
    p.mu.Lock()
    expected := !p.connected
    p.mu.Unlock()

    if expected {
        p.logger.Debug("websocket closed normally", slog.Any("err", err))
    } else {
        p.logger.Error("failed to read websocket message", slog.Any("err", err))
    }
    break
}

This way, intentional closures are logged at DEBUG level, while real unexpected errors remain at ERROR.

Why not websocket.IsUnexpectedCloseError?

use of closed network connection is a raw TCP-level error, not a WebSocket close frame. IsUnexpectedCloseError only handles proper WebSocket close codes and would not catch this case.