History Sync: Panic 'Election block must have validators'

[viquezclaudio]

In the private testnet (8xhistory-validators), the following panic was observed in validator-2:

thread 'tokio-runtime-worker' panicked at 'Election block must have validators': /home/nimiq/core-rs-albatross/consensus/src/sync/history/cluster.rs:223
The test conditions were as follows:

• Validator7 & Validator8 are tainted validators: They will respond with erroneous information to the different consensus requests (history chunk, head, missing blocks, etc. )
• All other validators are normal.
• Validator 2 was stopped, then its state was erased and then it was restarted. During the history sync process, this validator panicked.

It is important to note that many of the validator-2 chunks that this validator requested failed to verify due to the tainted validators:
HistoryChunk failed to verify
So this validator was trying to re-request many times the history chunks and then it panicked.

[viquezclaudio]

Attaching validator-2 logs:
privtestnet_validator2.log

[viquezclaudio]

Tainted validators logs as a reference:
privtestnet_validator7.log
privtestnet_validator8.log