[Access] Investigate gorrilla ReadJSON return error on Close

[Guitarheroua]

Due to comment #6907 (comment) we should remove duplication of error handling in WS controller code:

if err := c.conn.ReadJSON(&message); err != nil {
    // The check in `if` statement below should be removed
    if errors.Is(err, websocket.ErrCloseSent) {
	return err
    }
    var closeErr *websocket.CloseError
    if errors.As(err, &closeErr) {
        return err
    }

But we should ensure that ReadJSON always return *websocket.CloseError on close.