[BUG] Sumeragi panics with "index out of bounds" message after unregistering a peer

[0x009922]

OS and Environment

macOs 14.16.1

GIT commit hash

3e86d7b (in #5087)

Minimum working example / Steps to reproduce

Occured while re-implementing test network #5087, test connected_peers.rs integration test suite

1. Create network with 7 peers, start, wait for genesis
2. Unregister a random one

Actual result

Sometimes one of the remaining peers may panic:

thread 'sumeragi' panicked at crates/iroha_core/src/sumeragi/main_loop.rs:626:38:
index out of bounds: the len is 6 but the index is 6

At this index access:

iroha/crates/iroha_core/src/sumeragi/main_loop.rs

Line 626 in 7144f4e

let signatory = &self.topology.as_ref()[signatory_idx];

Expected result

Expected to not panic at any time.

Logs

https://pastebin.com/LXtRDLNe

Who can help to reproduce?

@0x009922

Notes

Used release target of Iroha.