为什么未定义的正确$标识符显示在错误日志中但不显示在UI中

class MPF_Miinto_Main
{
    private $sandbox;

    private $identifier;

    private $secret;

    public function __construct($config)
    {
        $this->sandbox = $config->sandbox;
        $this->identifier = $config->identifier;
        $this->secret = $config->secret;
    }

}

It shows:

PHP Notice: Undefined property: stdClass::$sandbox in /var/www/html/exportfeed/wp-content/plugins/woocommerce-miinto/core/classes/miinto-main.php on line 28 PHP Notice: Undefined property: stdClass::$identifier in /var/www/html/exportfeed/wp-content/plugins/woocommerce-miinto/core/classes/miinto-main.php on line 31 PHP Notice: Undefined property: stdClass::$secret in /var/www/html/exportfeed/wp-content/plugins/woocommerce-miinto/core/classes/miinto-main.php on line 32

Because you have display_errors set to 0.