Why are errors stored in the transaction logs?

[Sylvain Wallez]

Hi ZooKeepers,

We had an issue recently with a service hammering ZK to read a path that 
doesn't exist. As a result the transaction logs grew quickly because 
errors are stored there.

Looking at DataTree.processTxn() which is called from 
FileTxnSnapLog.restore() it seems that errors read in the transaction 
log are essentially ignored.

So what is storing errors in the txnlog useful for? Would it make sense 
to have a configuration flag to not store them?

Thanks,
Sylvain