Change `ArgIterator.next()` return type

Changes the return type of `ArgIterator.next()` from
`?(NextError![:0]u8)` to `NextError!?[:0]u8`.
7e16bb36d8ominitay committed on 12/21/2021, 7:15:33 PM· committed by Andrew Kelleyparent0d09b87
4 files changedLine totals unavailable