There's two problems with integer overflows: 1) undefined behavior (ugh), and 2) any defined behavior that is anything other than a) some behavior that you spec

There's two problems with integer overflows: 1) undefined behavior (ugh), and 2) any defined behavior that is anything other than a) some behavior that you specified as desired in code, or b) cause an -and force you to check for- error (or exception, ugh). Of these two, (1) is easily the worst, but where (1) is solved then (2) becomes the worse problem (naturally, being the only problem left).