Poor error message mocking a non-virtual Set property

[aufde]

Simple setup here, using Moq 4.16.1:

public class Blah
{
	public string Thing { get; set; }
}

public class BlahWrapper
{
	public virtual Blah Blah { get; set; }
	public string Thing { get => Blah.Thing; set => Blah.Thing = value; }
}

public class TestService
{
	public void Test(BlahWrapper blahWrapper)
	{
		blahWrapper.Thing = "";
	}
}

[Test]
public void ActualTest()
{
	var mock = new Mock<BlahWrapper>();
	mock
		.SetupSet(x => x.Thing = It.IsAny<string>())
		.Verifiable();

	new TestService().Test(mock.Object);
}

BlahWrapper.Thing is not virtual so this fails to setup but throws an unhelpful error, Could not determine the correct positions for all argument matchers (1 in total) used in a call to this method: ServiceRequestServiceTests.BlahWrapper.get_Blah.
Making BlahWrapper.Thing virtual allows the test to pass. In BlahWrapper, changing public string Thing { get => Blah.Thing; set => Blah.Thing = value; } to public string Thing { get; set; } correctly throws an error about it being non-virtual instead of the above, unhelpful error message.

[stakx]

Feel free to submit a PR. You'd quickly discover why this is absolutely non-trivial, as everything non-virtual or sealed is basically invisible to Moq 4. Nothing to be done here, the only options as far as I can tell is switching to Moq 5, or otherwise replace the internal matcher guessing machinery behind SetupSet with one that decompiles the passed lambda's IL bytecode.