Вылетает исключение и не работает программа - C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.IO;
 
namespace Program_Analizator
{
    class Program
    {
        [DataContract]
        public class Person
        {
            [DataMember]
            public string name { get; set; }
 
            [DataMember]
            public string lastname { get; set; }
 
            [DataMember]
            public Adress adress { get; set; }
 
            [DataMember]
            public string[] PhoneNumbers { get; set; }
        }
 
        [DataContract]
        public class Adress
        {
            [DataMember]
            public string StreetAdress { get; set; }
 
            [DataMember]
            public string city { get; set; }
 
            [DataMember]
            public int PostalCode { get; set; }
        }

        static void Main(string[] args)
        {
            MemoryStream write = new MemoryStream();
            Person person = new Person();
            DataContractJsonSerializer rer = new DataContractJsonSerializer(typeof(Person));
 
            person.name = "Иван";
            person.lastname = "Иванов";
            person.adress.StreetAdress = "Московское ш., 101, кв.101";
            person.adress.city = "Ленинград";
            person.adress.PostalCode = 101101;
            person.PhoneNumbers[0] = "812 123-1234";
            person.PhoneNumbers[1] = "916 123-4567";
 
            string path = @"Person.txt";
 
            rer.WriteObject(write, person);
 
            StreamWriter wr = new StreamWriter(path, false, System.Text.Encoding.UTF8);
            wr.WriteLine(rer);
            Console.ReadKey();
        }
    }
}