Extension (2.4.10+) Crashes on Init when calling DialogueRunner.AddFunction() with an instance method

[fmoo]

What is the current behavior?

When DialogueRunner.AddFunction<>() is called with an instance method, the extension crashes during initialization.

Please provide the steps to reproduce, and if possible a minimal demo of the problem:

Include this CustomExtensions.cs in your project

using UnityEngine;
using Yarn.Unity;

public class CustomExtensions : MonoBehaviour {
    [SerializeField] DialogueRunner runner;

    void Awake() {
        if (runner != null) InitializeRunner(runner);
    }

    public void InitializeRunner(DialogueRunner runner) {
        new ScopedExtensions(runner);
    }

    public class ScopedExtensions {
        private DialogueRunner thisRunner;
        public int Sub2(string varA, string varB) {
            thisRunner.VariableStorage.TryGetValue<int>(varA, out var a);
            thisRunner.VariableStorage.TryGetValue<int>(varB, out var b);
            return a - b;
        }

        public ScopedExtensions(DialogueRunner runner) {
            thisRunner = runner;
            thisRunner.AddFunction<string, string, int>("Sub2", Sub2);  // Crashes yarn
        }
    }
}

And a sample yarn file:

title: TestFile
---
<<declare $b = 0>>
<<set $b = Sub2("a", "b")>>
===

Open the .yarn file and observe the following error logs (one in a popup, one in the yarnspinner plugin console): https://pastebin.com/X29QAW6Z

What is the expected behavior?

The yarn extension loads and I can ctrl+click into Sub2 and jump to the implementation

Please tell us about your environment:

• Yarn Spinner Version: 2.2.2+git
• Extension Version: 2.4.10+
• Unity Version: 2021.3.12f1

Other information

https://pastebin.com/X29QAW6Z

[fmoo]

I believe this is the same trigger condition as #48, as the .yarn lines logs type checking errors on 2.4.9 and earlier.

[fmoo]

I believe this is the same trigger condition as #48, as the .yarn lines logs type checking errors on 2.4.9 and earlier.

This does not seem to be the case as I was able to get a structure that cmd+click and function syntax works OK on 2.4.9, but still crashes on newer versions.