Steps to reproduce the issue

Change "administrator" folder in "/includes/defines.php" and "/administrator/includes/defines.php" to "admin"
rename "administrator" folder to "admin"

Expected result

Everything working

Actual result

Error 500 - There is no "template.atum.ltr" asset of a "preset" type in the registry.

System information (as much as possible)

Joomla 5.x

Additional comments

Change "addTemplateRegistryFile" function in /libraries/src/WebAsset/WebAssetRegistry.php to:

    /**
     * Helper method to register new file with Template Asset(s) info
     *
     * @param   string   $template  The template name
     * @param   integer  $client    The application client id
     *
     * @return  self
     *
     * @since  4.0.0
     */
    public function addTemplateRegistryFile(string $template, int $client): self
    {
        switch ($client) {
            case 0:
            case 1:
                $this->addRegistryFile(str_replace(JPATH_ROOT . '/', '', JPATH_THEMES) . '/' . $template . '/joomla.asset.json');
                break;
            default:
                break;
        }

        return $this;
    }