ext_tables.php

<?php
defined('TYPO3_MODE') || die();

$boot = function ($_EXTKEY) {
    // Register TypoScript
    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addStaticFile($_EXTKEY, 'Configuration/TypoScript', 'OpenID Connect');
    if (\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::isLoaded('felogin')) {
        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addStaticFile($_EXTKEY, 'Configuration/TypoScript/felogin', 'OpenID Connect for felogin');
    }

    // Register hooks into \TYPO3\CMS\Core\DataHandling\DataHandler
    $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tcemain.php']['processDatamapClass'][] = \Causal\Oidc\Hooks\DataHandler::class;
};

$boot('oidc');
unset($boot);