Site Unavailable Page During Development

So here is some code that I think should work:

<?php
if ($modx->context->get("key") != "mgr") {
    if ($modx->event->name == "OnHandleRequest") {
        if (!$modx->checkSiteStatus()) {
            $forwardId = $modx->getOption('site_unavailable_page', null, 1);
            $modx->sendForward($forwardId);
        }
    }
}

It’s for the OnHandleRequest event.

(If you experience any problems with this code or don’t need the functionality any longer, just deactivate the plugin.)