pub fn error_code(code: i64) -> SwiftErrorExpand description
An Error holding one Int, for the cases that only need to say which.
The Error conformance is synthesised the same way every other one in this
crate is — Error has no requirements of its own beyond the defaults, so the
witness table is all defaults and the interesting part is that it is
registered, which is what makes the box catchable as an Error on the
Swift side.