class AlreadyInstalledException

class AlreadyInstalledException extends InstallerException {
    
    /**
     * Constructs a new "already installed" exception.
     *
     * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
     *   The string translation manager.
     */
    public function __construct(TranslationInterface $string_translation) {
        $this->stringTranslation = $string_translation;
        $title = $this->t('Drupal already installed');
        $replacements = [
            ':base-url' => $GLOBALS['base_url'],
            // We cannot use the route system.db_update here because we are too early
            // in the execution stack.
':update-url' => $GLOBALS['base_path'] . 'update.php',
        ];
        $message = $this->t('<ul>
<li>To start over, you must empty your existing database and copy <em>default.settings.php</em> over <em>settings.php</em>.</li>
<li>To upgrade an existing installation, proceed to the <a href=":update-url">update script</a>.</li>
<li>View your <a href=":base-url">existing site</a>.</li>
</ul>', $replacements);
        parent::__construct($message, $title);
    }

}