[tpoacher]

I'd say between a stupid result out of ignorance or risky defaults, vs a stupid result out of explicitly being stupid and overriding sane defaults, the latter is probably safer.

Also, exceptions (particularly checked ones) are not a simple matter of optional checks; they form an explicit contract forcing you to deal with exceptions (and having to be explicitly stupid to make them useless via an empty try/catch block). Compare to type-contracts where you'd need to go out of your way to make the "Null" part of the union type "useful" in the first place, for example.