Fare il logout quando la sessione è scaduta

[giannino1995]

Ho trovato un bug del mio programma.
Quando la sessione è scaduta e faccio un logout finisco in error.jsp.

<error-page>
    <exception-type>java.lang.Throwable</exception-type>
    <location>/error.jsp</location>
</error-page>

Perché accade questo e come risolvo?

package web1;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet(name = "ServletLogout", urlPatterns="/logout.jsp")
public class ServletLogout extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,
            IOException {
        HttpSession session = request.getSession(false);
        session.invalidate();
        response.sendRedirect("/index.jsp");
    }
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
            IOException {
response.sendRedirect("/index.jsp");
    }

}