I should not have used the word "assertion". I meant it in the more general way of "code that checks some property", not a literal "assert" feature as built in

I should not have used the word "assertion". I meant it in the more general way of "code that checks some property", not a literal "assert" feature as built in to the language. I was just pointing out that this bug basically requires an explicit test checking for exactly the bug. Fuzzing would not have found the check for you.