Unexpected error when deserializing unknown types

[blair-ahlquist]

In the following code, I serialize an object using Json.Net. This Json has type names embedded. I then change one of the type names to induce an error. When I deserialize the Json, I expect to get an object back that has a null value for the property with the fiddled type name. Instead the serializer craps out and returns null for the root object. The second error that I get suggests that there is a bug in the serializer.

static public class JsonTest
{
    static public void Test()
    {
        // Create test object
        A a = new A
        {
            MyTest = new MyTest(),
        };
      
        // Serialize it. 
        string json = JsonConvert.SerializeObject(a, new JsonSerializerSettings
        {
            TypeNameHandling = TypeNameHandling.Auto
        });

        // Fiddle class name to induce error
        json = json.Replace("+MyTest", "+MyTest2"); 

        // Before: {"MyTest":{"$type":"<Namespace>.JsonTest+MyTest, <Assembly>"}}
        // After: {"MyTest":{"$type":"<Namespace>.JsonTest+MyTest2, <Assembly>"}}

        // Deserialize
        A a2 = JsonConvert.DeserializeObject<A>(json, new JsonSerializerSettings
        {
            TypeNameHandling = TypeNameHandling.Auto,
            Error = (object sender, ErrorEventArgs e) =>
            {
                e.ErrorContext.Handled = true; // Should have only one error: the unrecognized Type
            }
        });

        // A second error occurs: Error = {Newtonsoft.Json.JsonSerializationException: Additional text found in JSON string after finishing deserializing object....
        // a2 is null
    }

    public class A
    {
        public ITest MyTest { get; set; }
    }

    public interface ITest { }
    public class MyTest : ITest { }
}

(This was posted as a question on stackoverflow.)

[JamesNK]

Fixed f88ae28