Json.NET错误处理似乎被打破了

Question

在某些情况下，序列化将输出无效的JSON字符串。

该行为似乎与“处理”错误有关，但JSON.NET使输出处于无效状态。

附上一个小程序来重现：

using System;
using System.Collections.Generic;
using System.Linq;
using Newtonsoft.Json;

namespace JsonNetBug
{
    class Program
    {
        static void Main()
        {

            var settings = new JsonSerializerSettings();
            settings.Error += (obj, args) =>
                {
                    args.ErrorContext.Handled = true;
                };

            var data = new List<Person>()
                {
                    new Person{FirstName = "Scott", LastName = "Hanselman"},
                    new Person{FirstName = "Scott", LastName = "Hunter"},
                    new Person{FirstName = "Scott", LastName = "Guthrie"},
                };


            var dictionary = data.GroupBy(person => person.FirstName).ToDictionary(group => @group.Key, group => @group.Cast<IPerson>());
            var output = JsonConvert.SerializeObject(dictionary, Formatting.None, settings);
            Console.WriteLine(output);
            Console.ReadLine();
        }
    }

    interface IPerson
    {

    }

    class Person//:IPerson - oops! Forgot to implement the person interface
    {
        public string LastName { get; set; }
        public string FirstName { get; set; }
    }
}

更新：

忘了提及它写出{"Scott":}时出现的格式错误。应该写出来的是{"Scott":null}