protected function validator($value)
    {
        $value = parent::validator($value);

        if ($this->hasErrors()) {
            return null;
        } elseif ($value == '') {
            if ($this->mandatory) {
                $this->addError(sprintf($GLOBALS['TL_LANG']['ERR']['mandatory'], $this->strLabel));
            }
        } elseif (!$this->iconExists($value)) {
            $this->addError(sprintf($GLOBALS['TL_LANG']['ERR']['iconNotFound'], $this->strLabel));
        }

        return $value;
    }