There is no easy way out when you're working with C: either you handle all possible UB cases with exhaustive checks, or you move on to another language.

(TIP: choose the latter)

For signed overflow you can just turn on the sanitizer in trapping mode. Exhaustive checks is also not that terrible.

Very few programming languages default to checked increments. Most Rust or Java programmers would make the same mistake.

Writing a function to do a checked addition like in other languages isn't exactly difficult, either.