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 NUL-terminated string.
let msg = unsafe { std::ffi::CStr::from_ptr(_out_error) }.to_string_lossy().into_owned();
if let Some(free_fn) = {{ vtable_expr }}.free_string {
// SAFETY: free_fn is the vtable-provided destructor for callback strings.
unsafe { free_fn(_out_error) };
}
msg
};
{{ error_return }}
}