Yet very simple, the valum-0.3/Valum.safely middleware provide a powerful way of discovering possible error conditions and handle them locally.

Only status defined in Redirection and Error are leaked: the compiler will warn for all other unhandled errors.

app.get ("/", safely ((req, res, next, ctx) => {
    try {
        res.expand_utf8 ("Hello world!");
    } catch (IOError err) {
        critical (err.message);
        return false;