fix NPE

wrapper_client.go

@@ -15,12 +15,11 @@ import (
 	"git.zhangdeman.cn/zhangdeman/database/abstract"
 	"git.zhangdeman.cn/zhangdeman/database/define"
 	"git.zhangdeman.cn/zhangdeman/serialize"
+	"go.uber.org/zap"
 	"path/filepath"
 	"strings"
 	"sync"
 
-	"go.uber.org/zap"
-
 	"gorm.io/gorm"
 )
 
@@ -184,6 +183,7 @@ func (c *wrapperClient) GetMasterClient(ctx context.Context, dbFlag string) (*go
 	if dbClient, err = c.GetDBClient(dbFlag); nil != err {
 		return nil, err
 	}
+
 	return dbClient.GetMaster(ctx), nil
 }