使用all模式同步时，日志中出现run splitVector failed[cannot Decode to nil value], give up parallel fetching

[xiang-coco]

1.MongoShake的版本：2.8.4
2.源和目的MongoDB的版本：4.2.17
3. 脱敏后的日志文件
4. mongoshake相关参数：
SyncMode=all
full_sync.reader.parallel_thread=4
filter.ddl_enable = true
full_sync.create_index = background
full_sync.collection_exist_drop = true
5.mongoshake服务器配置：2C 8G

6.同步时日志中存在如下警告
[2023/07/03 13:30:47 CST] [WARN]
splitter[DocumentSplitter src[mongodb://username:password@192.168.0.2:3091,192.168.0.3:3091,192.168.0.1:3019] ns[{schema test}]
count[8002255] pieceByteSize[492 MB] pieceNumber[0]] run splitVector failed[cannot Decode to nil value], give up parallel fetching