silkworm: unexpected termination during tip sync

Running standalone Silkworm at commit 7912b0d64ee18513ac65a6a610e5b47e4dbc5a3c an unexpected termination occurred while syncing the chain tip:
```
...
INFO [09-09|15:14:17.666 UTC] sync::SentryClient Peer e086e2c976763cfe1a0fb1ec3af1b718acf92f36 disconnected, active 62, info: -info-not-found-
INFO [09-09|15:14:22.274 UTC] sync::SentryClient Peer 99a41be45d02b1840193879244e6d540a0df7c92 connected, active 63, info: client_id=erigon/v2.60.4-72ab70be/linux-amd64/go1.22.5 / enode_url=enode://99a41be45d02b1840193879244e6d540a0df7c923e301e6cce6ec452b98332c881b647b3d9976648115bac169206e3e3461742645401663b7b1d1a7bed1c4733@129.159.205.177:30303
INFO [09-09|15:14:22.289 UTC] sync::SentryClient Peer 1cf7db662897dcd2af946fdd47e5b6d8273846e6 connected, active 64, info: client_id=Nodecrawler/v1.14.0-unstable/linux-amd64/go1.22.5 / enode_url=enode://1cf7db662897dcd2af946fdd47e5b6d8273846e6a6bef4f1f3ec1f2b38c77c6a2382fb9409e43681c15cc043298d9476f2faa14c1adb805c15559e616ff4c361@3.10.19.215:30318
INFO [09-09|15:14:22.466 UTC] sync::SentryClient Peer 98dd88d8b72fb3afb13447c15758d07d0a330b80 disconnected, active 63, info: -info-not-found-
INFO [09-09|15:14:24.726 UTC] PoSSync: fork_choice_update head_block_hash=01fa18ba3928852fe0c4609f36f231f2b55cb68cce1c4919d35bea428be710a4 safe_block_hash=f708d99bdb9552ea90533a407efff87b7c389f6e65073e92391a9c3ac50f9641 finalized_block_hash=7b7333016e6696ef12c35f478bd66a9c45425e1d4743017e732156bb09332297
INFO [09-09|15:14:24.730 UTC] PoSSync: fork_choice_update head header not found => SYNCING
INFO [09-09|15:14:33.661 UTC] sync::SentryClient Peer b42b492d2681ffc6b23516b8e7e3bfe422c8cc48 connected, active 64, info: client_id=Nethermind/v1.25.2+78c7bf5f/linux-x64/dotnet8.0.1 / enode_url=enode://b42b492d2681ffc6b23516b8e7e3bfe422c8cc4809037b352f088eb7c159277fdc892b55114d84da39febdb88a9928090b2c9540f8b7a1e01e115572b302cfc9@141.95.35.226:30303
CRIT [09-09|15:14:37.105 UTC] ContextPool context.execute_loop exception: co_await: Operation canceled [system:125]
CRIT [09-09|15:14:37.105 UTC] Silkworm terminating due to exception: co_await: Operation canceled [system:125]
```
The Consensus Layer client was active and driving the chain sync as shown below in Silkworm interface logs:
```
...
[2024-09-09 15:14:24.638] RSP <- {"id":11,"jsonrpc":"2.0","result":{"status":"SYNCING"}}
[2024-09-09 15:14:24.726] REQ -> {"jsonrpc":"2.0","id":12,"method":"engine_forkchoiceUpdatedV3","params":[{"headBlockHash":"0x01fa18ba3928852fe0c4609f36f231f2b55cb68cce1c4919d35bea428be710a4","safeBlockHash":"0xf708d99bdb9552ea90533a407efff87b7c389f6e65073e92391a9c3ac50f9641","finalizedBlockHash":"0x7b7333016e6696ef12c35f478bd66a9c45425e1d4743017e732156bb09332297"},null]}
[2024-09-09 15:14:24.730] RSP <- {"id":12,"jsonrpc":"2.0","result":{"payloadStatus":{"status":"SYNCING"}}}
```