I think that's a silly definition of a bug. If it breaks the product, it's a bug. It doesn't matter if it was created at dev time or design time. Hell, a huge

I think that's a silly definition of a bug. If it breaks the product, it's a bug. It doesn't matter if it was created at dev time or design time. Hell, a huge chunk of dev work is rethinking design decisions that are misguided/under specified/break things because you only see these issues once you start having to implement details.