So yeah that small not hit portion of code can always be a time bomb if it does not get tested...
That has nothing to do with the language, and can happen in any language.
I did a 5 year stint of no sugar except for one cheat day a month.
My rules were: Fruit and milk OK No products with honey, sugar, high fructose corn syrup etc.
The first 2 weeks are the hardest then it is pretty easy to do...
So yeah that small not hit portion of code can always be a time bomb if it does not get tested...