未捕获异常'；异常'；带有消息'；*GET属性登录不存在'；谁能给我解决办法吗

我收到这个错误

致命错误：

未捕获异常"exception"，消息为"*GET属性登录"中不存在E： ''examplep''htdocs''UniversityWork''Project''UniversityProjectPHP''model''Checkout.php：30堆栈跟踪：#0E： ''examplep''htdocs''UniversityWork''Project''UniversityProjectPHP''views''top.php（44）：结账->__get（'登录'）#1

E： ''examplep''htdocs''UniversityWork''Project''UniversityProjectPHP''checkout.php（9）：require_one（'E:''examplep''htdocs…'）抛出#2｛main｝E： ''examplep''htdocs''UniversityWork''Project''UniversityProjectPHP''model''Checkout.php在线30

第44行看起来像这个

if ($obj_user->login && in_array($current, $public_pages)) {
$_SESSION['ref_url'] = $url;
$_SESSION['msg'] = "You must <a href='" . BASE_URL .    "process/process_logout.php'>LOGOUT</a> to view this page";
header("Location:" . BASE_URL . "msg.php");
}

第30行看起来像

public function __get($name) {
    $method_name = "get_$name";
    if (!method_exists($this, $method_name)) {
        **throw new Exception(" * GET Property $name does not exist");**
    }
    return $this->$method_name();
}

第9行看起来像这个

<title> Home shop || Checkout </title>
<?php
require_once 'model/user.php';
require_once 'model/brand.php';
require_once 'model/Checkout.php';
require_once 'model/product.php';
require_once 'model/cart.php';
require_once 'model/category.php';
**require_once 'views/top.php';**
require_once 'model/web_interface.php';
?>