lib/server.js
function ifError(n) {
    function _ifError(err) {
        if (err) {
            err._rpc_next = n;
            throw err;
        }
    }

    return (_ifError);
}
function ifError(n) {
    function _ifError(err) {
        if (err) {
            err._rpc_next = n;
            throw err;
        }
    }

    return (_ifError);
}
/--- Private Methods "this" is bound to an RpcServer