not sure I agree. UB has the benefit that there are a lot of tools like valgrind, memcheck, and various compiler features to detect it both statically and at ru

not sure I agree. UB has the benefit that there are a lot of tools like valgrind, memcheck, and various compiler features to detect it both statically and at runtime. And when you hit UB it is certainly an error. Non-UB errors have no such powerful tools, only what application specific tests or assertions you create. I've seen plenty of cases where people went and turned signed types into unsigned because signed overflow is undefined, but it had the real effect of turning easily detected and diagnosed issues into much harder to find bugs.