intellij javaWeb项目 运行的时候有错，为什么outPut中不打印错误？?报错

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = request.getParameter("userName");
        String pwd =  request.getParameter("userPwd");
        System.out.print("start "); int a = 1 / 0;//这里应该报错的。。。 if( name.equals(pwd)){
            response.sendRedirect("/index.jsp?name=" + name);
        }else{
            response.sendRedirect("login.jsp");
        }

    }