错误代码修正

src/server/models/sessions/sessions.js

@@ -330,7 +330,10 @@ class Sessions extends RedisModel {
        let participants = new Participants();
        let offset = (page - 1 < 0 ? 0 : page - 1) * size;
        let count = size + 1;
        let count = size;
        if(page>1||startMsgId){//翻页由于闭区间，需跳过本身数据
            offset +=1;
        }
        participants.existsParticipant(sessionId, userId, function (err, res) {
            if (!res) {