This is inconsistent code to being with, though. You can't guarantee it "never" reaches the first branch, as much as you can't guarantee there aren't bugs in the conversion function, or on the underlying interpreter, or that machine details wouldn't make a big enough number wrap around and return negative. All in all, an inconsistent code branch hanging around is a bug even if it compiles.
This is more an evidence that "if" is evil rather than an argument about typing, really.
This is inconsistent code to being with, though. You can't guarantee it "never" reaches the first branch, as much as you can't guarantee there aren't bugs in the conversion function, or on the underlying interpreter, or that machine details wouldn't make a big enough number wrap around and return negative. All in all, an inconsistent code branch hanging around is a bug even if it compiles.
This is more an evidence that "if" is evil rather than an argument about typing, really.