Default arguments from a delegate definition are ignored.

[rgalex2034]

Hello,

I've noticed that when adding a delegate to a ScriptObject, it ignores the default arguments from the delegate definition and checks againts the arguments of the anonymous function/method used to create the delegate.

For example:

class SomeNewContext : ScriptObject
{
    public delegate void SomeDelegate(string text = "default");

    public SomeNewContext(SomeDelegate del)
    {
        this["scriban_function"] = del;
    }
}

In this case, it will ignore the default argument if I use something like new SomeNewContext(text => text.ToUpper()).

I've been checking why it happens and it's because it uses the delegate.Method to check against the arguments, and those may differ from the delegate.Invoke() call.
(https://github.com/scriban/scriban/blob/master/src/Scriban/Runtime/DelegateCustomFunction.cs#L27)

As a workaround I've found, wrapping the delegate on itself makes the delegate.Method return the signature of the delegate, like this: this["scriban_function"] = new SomeDelegate(del); in the example above.