Quote Originally Posted by swguy View Post
I guess what I'm wondering is, if it's possible to deduce that you're in this state and give a message to the customer in the cart.
how do you know i'm not already doing that?

error messages are already added to the message stack and displayed to the customer. see:

https://github.com/proseLA/square_we....php#L428-L433

line 431.