Problem in 5.3.8

<?PHP
print ILLI_Constructeur::get_Instance(self::c_CNSTCNFG)->_ENVIRONMENT_MODE; // 'PRODUCTION'
?>
run:
<?PHP
            if(ILLI_Constructeur::get_Instance(self::c_CNSTCNFG)->_ENVIRONMENT_MODE == 'PRODUCTION')
                print 'email';
            else
                print 'exception';
?>

expected: email
actual: email


bug:
<?PHP
            if(isset(ILLI_Constructeur::get_Instance(self::c_CNSTCNFG)->_ENVIRONMENT_MODE)
            && ILLI_Constructeur::get_Instance(self::c_CNSTCNFG)->_ENVIRONMENT_MODE == 'PRODUCTION')
                print 'email';
            else
                print 'exception';
?>
expected: email
actual: exception


solution:
<?PHP
            if(ILLI_Constructeur::get_Instance(self::c_CNSTCNFG)->offsetExists('ENVIRONMENT_MODE')
            && ILLI_Constructeur::get_Instance(self::c_CNSTCNFG)->_ENVIRONMENT_MODE == 'PRODUCTION')
                print 'email';
            else
                print 'exception';
?>


The original-code
<?PHP

    ABSTRACT CLASS ILLI_Container_Abstract IMPLEMENTS ILLI_Container_Interface, ILLI_Interface
    {
        /**
         * data-cache
         *
         * @var array
         */
        private $cache
            = array();


        /**
         * @param $name string var-name
         * @return bool if offset exists in {@link ILLI_Container_Abstract::$cache} or getter-method exists
         */
        public function __isset($name)
        {
            if($name{0} === '_')
                return $this->offsetExists
                (
                    substr
                    (
                        $name,
                        1
                    )
                );
            else
                return $this->methodExists($name);
        }

        /**
         * @param $name string var-name
         * @return  bool array-key exists in {@link ILLI_Container_Abstract::$cache}
         */
        public function offsetExists($name)
        {
            $name =
                str_replace
                (
                    '-',
                    '_',
                    $name
                );

            return array_key_exists
            (
                $name,
                $this->cache
            );
        }

...