if _rc != 0 {
let msg = if _out_error.is_null() {
format!("vtable.{{ name }} returned error code {}", _rc)
} else {
// SAFETY: out_error was written by the callee as a valid CString.
let cs = unsafe { std::ffi::CString::from_raw(_out_error) };
cs.to_string_lossy().into_owned()
};
{{ error_return }}
}