اخطار کلوژر در sluggable

من یک تابع برای اینکه اسلاگ زمانی که فارسی هست تبدیل به یک رشته بی معنی با حروف انگلیسی نشه داخل sluggable.php در کانفیک نوشتم اما در هنگام کش کردن این اخطارو دریافت میکنم:
‍‍‍your configuration files are not serializable
راه حل دیگه ای نیست؟ داخل توضیحات پکیج هم نوشته میشه یک فانکشن سفارشی نوشت اما این اخطارو چطور میشه رفع کرد؟
فانکشن هم این هست :

    'method' => function($string, $separator = '-') {
        $_transliteration = ["/ö|œ/" => "e",
            "/ü/" => "e",
            "/Ä/" => "e",
            "/Ü/" => "e",
            "/Ö/" => "e",
            "/À|Á|Â|Ã|Å|Ǻ|Ā|Ă|Ą|Ǎ/" => "",
            "/à|á|â|ã|å|ǻ|ā|ă|ą|ǎ|ª/" => "",
            "/Ç|Ć|Ĉ|Ċ|Č/" => "",
            "/ç|ć|ĉ|ċ|č/" => "",
            "/Ð|Ď|Đ/" => "",
            "/ð|ď|đ/" => "",
            "/È|É|Ê|Ë|Ē|Ĕ|Ė|Ę|Ě/" => "",
            "/è|é|ê|ë|ē|ĕ|ė|ę|ě/" => "",
            "/Ĝ|Ğ|Ġ|Ģ/" => "",
            "/ĝ|ğ|ġ|ģ/" => "",
            "/Ĥ|Ħ/" => "",
            "/ĥ|ħ/" => "",
            "/Ì|Í|Î|Ï|Ĩ|Ī| Ĭ|Ǐ|Į|İ/" => "",
            "/ì|í|î|ï|ĩ|ī|ĭ|ǐ|į|ı/" => "",
            "/Ĵ/" => "",
            "/ĵ/" => "",
            "/Ķ/" => "",
            "/ķ/" => "",
            "/Ĺ|Ļ|Ľ|Ŀ|Ł/" => "",
            "/ĺ|ļ|ľ|ŀ|ł/" => "",
            "/Ñ|Ń|Ņ|Ň/" => "",
            "/ñ|ń|ņ|ň|ʼn/" => "",
            "/Ò|Ó|Ô|Õ|Ō|Ŏ|Ǒ|Ő|Ơ|Ø|Ǿ/" => "",
            "/ò|ó|ô|õ|ō|ŏ|ǒ|ő|ơ|ø|ǿ|º/" => "",
            "/Ŕ|Ŗ|Ř/" => "",
            "/ŕ|ŗ|ř/" => "",
            "/Ś|Ŝ|Ş|Ș|Š/" => "",
            "/ś|ŝ|ş|ș|š|ſ/" => "",
            "/Ţ|Ț|Ť|Ŧ/" => "",
            "/ţ|ț|ť|ŧ/" => "",
            "/Ù|Ú|Û|Ũ|Ū|Ŭ|Ů|Ű|Ų|Ư|Ǔ|Ǖ|Ǘ|Ǚ|Ǜ/" => "",
            "/ù|ú|û|ũ|ū|ŭ|ů|ű|ų|ư|ǔ|ǖ|ǘ|ǚ|ǜ/" => "",
            "/Ý|Ÿ|Ŷ/" => "",
            "/ý|ÿ|ŷ/" => "",
            "/Ŵ/" => "",
            "/ŵ/" => "",
            "/Ź|Ż|Ž/" => "",
            "/ź|ż|ž/" => "",
            "/Æ|Ǽ/" => "E",
            "/ß/" => "s",
            "/IJ/" => "J",
            "/ij/" => "j",
            "/Œ/" => "E",
            "/ƒ/" => ""];
        $quotedReplacement = preg_quote($separator, '/');
        $merge = [
            '/[^\s\p{Zs}\p{Ll}\p{Lm}\p{Lo}\p{Lt}\p{Lu}\p{Nd}]/mu' => ' ',
            '/[\s\p{Zs}]+/mu' => $separator,
            sprintf('/^[%s]+|[%s]+$/', $quotedReplacement, $quotedReplacement) => '',
        ];
        $map = $_transliteration + $merge;
        unset($_transliteration);
        return preg_replace(array_keys($map), array_values($map), $string);
    },