Hi Amichai,

prior to the change of disallowing nullables this code worked fine:

  public static ErrorOr<Inspektionsvertrag?> TryCreateOrNull(int? freikilometer, int? freimonate)
    {
        if (freimonate is null or 0 && freikilometer is null or 0)
        {
            return  (Inspektionsvertrag?)null; //this used to work
        }
     ...

now I get the Argument-Null-Exception. So in my Use-Case not having values at all is fine and should not be an error.

A second issue realted to the same topic is a method with the following signature

 public static ErrorOr<Laufleistungslinie> TryCreate(int? a, int? b,  ErrorOr<Vorbesitzer>? vorbesitzer = null) 

prior to the change could be called with null as third parameter

var laufleistungslinie = Laufleistungslinie.TryCreate(20, 20, null);

this now also does a cast (although the whole errorOr<> is nullable, not only the T) and then throws null.

I would assume that being able to use nullables either on ErrorOr? or ErrorOr<T?> should be supported, but disallowing both is a bit too strict.

Hope my examples clarify my point. if not, please let me know