改进__unserialize方法

Author: liu21st

src/Model.php

@@ -827,6 +827,10 @@ public function __serialize(): array
      */
     public function __unserialize(array $data) 
     {
+        if (!self::$weakMap) {
+            self::$weakMap = new WeakMap;
+        }
+
         self::$weakMap[$this] = $data;
         // 重新初始化
         $this->initialize();