Smoldot panic after initial parachain sync if the chain object was removed

[voliva]

After updating PAPI to use 3.1.1, I've seen in the dapps I've upgraded that smoldot panics after syncing. I'm still not sure why, but so far it only happens in browser (i.e. the PAPI CLI doesn't have any issue connecting to a parachain)

Smoldot will take some time to initialize, and then panic with:

Smoldot has panicked while executing task `runtime-asset-hub-polkadot`. This is a bug in smoldot. Please open an issue at https://github.com/smol-dot/smoldot/issues with the following message:
panicked at /__w/smoldot/smoldot/light-base/src/runtime_service.rs:1689:78:
called `Option::unwrap()` on a `None` value

Logs 3.1.1 (KO)
smoldot_3.1.1.txt

Logs 3.1.0 (OK)
smoldot_3.1.0.txt

[voliva]

I investigated a bit more, and the browser has nothing to do with that, it was the setup.

If you have a script that:

• Creates a relay chain Chain object (e.g. polkadot)
• Creates a parachain Chain object (e.g. polkadot asset hub)
• Calls .remove() on the parachain before it's fully synced

Then once smoldot syncs, it will panic with that

import { chainSpec as polkadotChainSpec } from "polkadot-api/chains/polkadot";
import { chainSpec as assetHubChainSpec } from "polkadot-api/chains/polkadot_asset_hub";
import { start } from "smoldot";

const smoldot = start();

const relayChain = await smoldot.addChain({
  chainSpec: polkadotChainSpec,
});

const assetHubChain = await smoldot.addChain({
  chainSpec: assetHubChainSpec,
  potentialRelayChains: [relayChain],
});

assetHubChain.remove();

[smoldot] Smoldot v3.1.1
[smoldot] Chain initialization complete for polkadot. Name: "Polkadot". Genesis hash: 0x91b1…90c3. Chain specification starting at: 0x8fb8…4975 (#31012806)
[smoldot] Parachain initialization complete for asset-hub-polkadot. Name: "Polkadot Asset Hub". Genesis hash: 0x68d5…de2f. Relay chain: polkadot (id: 1000)
[smoldot] Shutting down chain asset-hub-polkadot
[runtime-polkadot] Successfully compiled runtime. Spec version: 2002001. Size of `:code`: 1.6 MiB.
[sync-service-asset-hub-polkadot] Waiting for relay chain to finalize a block...
[runtime-polkadot] Finalized block runtime ready. Spec version: 2002001. Size of `:code`: 1.6 MiB.
[runtime-polkadot] Successfully compiled runtime. Spec version: 2002001. Size of `:code`: 1.6 MiB.
[sync-service-asset-hub-polkadot] Got parachain head from relay chain: block #15173644, hash 0xd88c…be9d
[sync-service-asset-hub-polkadot] Fetched parachain finalized head from relay chain at block #15173644
[sync-service-asset-hub-polkadot] Bootstrapping parachain consensus from block #15173644 (0xd88c…be9d)
[sync-service-asset-hub-polkadot] Downloading parachain runtime from peer 12D3KooWKbfY9a9oywxMJKiALmt7yhrdQkjXMtvxhhDDN23vG93R
[sync-service-asset-hub-polkadot] Downloaded parachain runtime (2195686 bytes), compiling...
[sync-service-asset-hub-polkadot] Parachain uses Aura consensus (slot_duration=12000ms, authorities=15)
[runtime-asset-hub-polkadot] Finalized block runtime ready. Spec version: 2002001. Size of `:code`: 2.1 MiB.
Smoldot has panicked while executing task `runtime-asset-hub-polkadot`. This is a bug in smoldot. Please open an issue at https://github.com/smol-dot/smoldot/issues with the following message:
panicked at /__w/smoldot/smoldot/light-base/src/runtime_service.rs:1689:78:
called `Option::unwrap()` on a `None` value

Also confirming that this happens only with 3.1.1. With 3.1.0 doesn't crash and gives the following logs:

[smoldot] Smoldot v3.1.0
[smoldot] Chain initialization complete for polkadot. Name: "Polkadot". Genesis hash: 0x91b1…90c3. Chain specification starting at: 0x8fb8…4975 (#31012806)
[smoldot] Parachain initialization complete for asset-hub-polkadot. Name: "Polkadot Asset Hub". Genesis hash: 0x68d5…de2f. Relay chain: polkadot (id: 1000)
[smoldot] Shutting down chain asset-hub-polkadot
[runtime-polkadot] Successfully compiled runtime. Spec version: 2002001. Size of `:code`: 1.6 MiB.
[sync-service-asset-hub-polkadot] Waiting for relay chain to finalize a block...
[runtime-polkadot] Finalized block runtime ready. Spec version: 2002001. Size of `:code`: 1.6 MiB.
[runtime-polkadot] Successfully compiled runtime. Spec version: 2002001. Size of `:code`: 1.6 MiB.
[sync-service-asset-hub-polkadot] Got parachain head from relay chain: block #15173664, hash 0x9a39…efb3
[sync-service-asset-hub-polkadot] Fetched parachain finalized head from relay chain at block #15173664
[sync-service-asset-hub-polkadot] Bootstrapping parachain consensus from block #15173664 (0x9a39…efb3)
[sync-service-asset-hub-polkadot] Downloading parachain runtime from peer 12D3KooWNWF2zwxWDuZfXEzL29yeXAAubFy8tCCMjPwWLCZdLRqc
[sync-service-asset-hub-polkadot] Downloaded parachain runtime (2195686 bytes), compiling...
[sync-service-asset-hub-polkadot] Parachain uses Aura consensus (slot_duration=12000ms, authorities=15)

@replghost you've fixed a panic on unfollow recently, right? Maybe this is related? I'm not sure what could be the cause of this, the only changes in 3.1.1 are #3194 and #3203