private static function getFileContents(string $filePath): ?string
    {
        // Leave the stage early when 'Unknown' is passed
        // this would otherwise raise an exception when
        // open_basedir is enabled.
        if ($filePath === 'Unknown') {
            return null;
        }

        // Return null if the file doesn't actually exist.
        if (! \is_file($filePath)) {
            return null;
        }

        return \file_get_contents($filePath);
    }