Passing value from a different app domain to the primary (Main) app domain

From this post, I am able to load a dll into an app domain and get the types in that dll and print them in the temporary domain's function if I want to. But I now want to pass these types back to the primary domain (which has Main). I found this thread which says I need to wrap my object in a MarshalByRef type of class and pass it as an argument, and I tried that but I get an exception. Here is what I have (slightly modified from the example given by @Scoregraphic in the first linked thread)

    public class TypeListWrapper : MarshalByRefObject
    {
            public Type[] typeList { get; set; }
    }

    internal class InstanceProxy : MarshalByRefObject
    {
        public void LoadLibrary(string path, TypeListWrapper tlw)
        {
            Assembly asm = Assembly.LoadFrom(path);

            var x = asm.GetExportedTypes();//works fine

            tlw.typeList = x;//getting exception on this line
        }
    }

    public class Program
    {

        public static void Main(string[] args)
        {
            string pathToDll = Assembly.GetExecutingAssembly().Location;
            string path = "/path/to/abc.dll";

            try
            {
                AppDomainSetup domainSetup = new AppDomainSetup
                {
                    PrivateBinPath = pathToDll
                };
                AppDomain domain = AppDomain.CreateDomain("TempDomain", null, domainSetup);
                InstanceProxy proxy = domain.CreateInstanceFromAndUnwrap(pathToDll, typeof(InstanceProxy).FullName) as InstanceProxy;
                TypeListWrapper tlw = new TypeListWrapper();
                if (proxy != null)
                {
                    proxy.LoadLibrary(path, tlw);
                }


                AppDomain.Unload(domain);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message + Environment.NewLine + ex.StackTrace);
            }

            Console.ReadLine();
        }
    }

I get the exception:

Could not load file or assembly 'abc, Version=1.0.0.5, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.

If I remove the tlw argument from the function and remove this assignment, it works just fine. I'm completely stumped on this.