Ensure Arguments are never null

[ghost]

While running some unit tests using a PersistentActor a NullReferenceException was encountered. The culprit seems to be that when producer.Produce() throws an exception, the creation of the TypeLoadException throws a NullReferenceException when Arguments is null. The relevant excerpt from Props lines 568-577

        public virtual ActorBase NewActor()
        {
            var type = Type;
            var arguments = Arguments;
            try {
                return producer.Produce();
            } catch (Exception e) {
                throw new TypeLoadException($"Error while creating actor instance of type {type} with {arguments.Length} args: ({StringFormat.SafeJoin(",", arguments)})", e);
            }
        }

This fix ensures that no matter how the Props is constructed, Arguments will not be null fixing the above issue. This problem might be related to issue #2026.

[Aaronontheweb]

LGTM

[Aaronontheweb]

Test failure was unrelated - re-running it now.