[candiodari]

Yes, there is no problem as long as you agree with X about what is a "real" error and what isn't.

X includes

the language authors (who are using this more and more in the stdlib as pointed out elsewhere)

the authors of any library you use ... but

transitively, so this includes the authors of any library you use indirectly as well

Hmmmm ... what was the problem with (unchecked, or python's) exceptions again ?