添加 must_get 的错误返回值

session_get.go

@@ -23,6 +23,8 @@ func (session *Session) Get(bean interface{}) (bool, error) {
 	return session.get(bean)
 }
 
+var NoData = errors.New("no data found")
+
 func (session *Session) MustGet(bean interface{}) error {
 	if session.isAutoClose {
 		defer session.Close()
@@ -32,7 +34,7 @@ func (session *Session) MustGet(bean interface{}) error {
 		return err
 	}
 	if !ok {
-		return errors.New("no data found")
+		return NoData
 	}
 	return nil
 }