una/plugins_public/onesignal/OneSignalSDKWorker.js.php

<?php
/**
 * Note: This file is intended to be publicly accessible.
 * Reference: https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API/Using_Service_Workers
 */
header("Service-Worker-Allowed: /");
header("Content-Type: application/javascript");
header("X-Robots-Tag: none");
echo "importScripts('https://cdn.onesignal.com/sdks/OneSignalSDK.js');";