Error Handling & Error Definition Statement

[tahadostifam]

Ideas:

error UserErr(struct { id: uint32 }) {
    Unauthorized   = struct { id = 1 },
    DuplicateEmail = struct { id = 2 },
}

error UserErr(int, char*) {
    Unauthorized   = (403, "unauthorized"),
    DuplicateEmail = (401, "duplicate email"),
}

error UserErr {
    Unauthorized,
    DuplicateEmail
}

What if we make the Error Data Structure Declaration using by a strong support of macros?