Function in3_sys::ctx_set_error_intern

pub unsafe extern "C" fn ctx_set_error_intern(
    c: *mut in3_ctx_t, 
    msg: *mut c_char, 
    errnumber: Type
) -> Type

sets the error message in the context.

If there is a previous error it will append it. the return value will simply be passed so you can use it like

  return ctx_set_error(ctx, "wrong number of arguments", IN3_EINVAL)