异常类规范 增加异常类 改进Query类的value和column的缓存冲突问题

library/think/Session.php

@@ -11,6 +11,8 @@
 
 namespace think;
 
+use think\exception\ClassNotFoundException;
+
 class Session
 {
 
@@ -92,7 +94,7 @@ class Session
 
             // 检查驱动类
             if (!class_exists($class) || !session_set_save_handler(new $class($config))) {
-                throw new \think\Exception('error session handler', 11700);
+                throw new ClassNotFoundException('error session handler');
             }
         }
         if ($isDoStart) {