NullReferenceException with FastExpressionCompiler

[christophwille]

Sample with FastExpressionCompiler usage commented out, working as expected:

using FastExpressionCompiler;
using Mapster;

// TypeAdapterConfig.GlobalSettings.Compiler = exp => exp.CompileFast();

TypeAdapterConfig<TestClass, TestEnum>
    .NewConfig()
    .Map(dest => dest, src => src.Type == (int)TestEnum.A
       ? TestEnum.A
       : src.Type == (int)TestEnum.B
           ? TestEnum.B
           : src.Type == (int)TestEnum.C
               ? TestEnum.C
               : TestEnum.D);

var testClass = new TestClass { Type = 1 };
Console.WriteLine(testClass.Type);

var testEnum = testClass.Adapt<TestEnum>();
Console.WriteLine(testEnum);

class TestClass
{
    public int Type { get; set; }
}

enum TestEnum
{
    A = 1,
    B,
    C,
    D
}

With the line uncommented though, I get (on line var testEnum = testClass.Adapt<TestEnum>();)

System.NullReferenceException
  HResult=0x80004003
  Message=Object reference not set to an instance of an object.
  Source=<Cannot evaluate the exception source>
  StackTrace:
<Cannot evaluate the exception stack trace>

Is this a known limitation, a problem in Mapster, a problem in FastExpressionCompiler, ...? If this is a low-level bug, do you know of a workaround? Thanks.

[dadhi]

@christophwille The issue is fixed on the FEC side and will be released with the next v4.2.0