fix send message return

service/imService.go

@@ -34,8 +34,8 @@ func CreateGeneralMessageService(from_id, to_id, msg_type int, content string) (
 	case 4:
 		res, _ := dao.GetMsgUserByIndex(from_id, to_id, 4, 1, 0)
 		if len(res) > 0 {
-			// 已经有会话记录
-			return errors.New("already have a conversation"), 0
+			// 已经有会话记录,返回会话id
+			return nil, res[0].ID
 		}
 		err, id = dao.CreateGeneralMessage(from_id, to_id, msg_type, 0, 0, content)
 	case 5: