优化session方法

index.js

@@ -80,18 +80,17 @@ export default class Controller {
 
   // 会话读写
   session(key, val) {
-    let { enabled } = this.context.get('session')
     let { ssid } = this.request
-    if (enabled) {
+    if (this.context.$$session) {
+      key += ''
+
       if (arguments.length < 2) {
         // 这里返回的是Promise对象
         return this.context.$$session.get(ssid, key)
       }
-
-      key += ''
       this.context.$$session.set(ssid, key, val)
     } else {
-      throw Error('Session was disabled.')
+      throw new Error('Session was disabled.')
     }
   }
 }