private Player registerPlayer(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Player player = new Player(request.getParameter("name"),
request.getParameter("dateOfBirth"),
request.getParameter("password"));
String validationError = player.validationError();
if (validationError != null) {
request.getSession().invalidate();
viewIndex(request, response, validationError);
player = null;
} else {