Greetings. Don't ever feel like you're bugging me by reporting an issue like this, it's no trouble at all. It's my fault, really, as this is definitely a bug I introduced in the last update.
I'm not at a computer right now, but when I get home in a few hours, I'll look into it. Given the error message, I forgot to account for an empty hand when an actor was dual wielding, something which I thought I'd accounted for, but I must've missed a check.
Like I said, I'll look into it when I get home in a few hours and post an update.