Removing a chain causes smoldot to crash/panic

[kratico]

In NodeJS (or in a browser), the smoldot client crashes if a chain is removed while awaiting for chain.nextJsonRpcResponse().

The issue is reproduced in this stackblitz with the following code

import * as smoldot from 'smoldot';
import fs from 'node:fs';

// Load a string chain specification.
const chainSpec = fs.readFileSync('./westend.json', 'utf8');

// A single client can be used to initialize multiple chains.
const client = smoldot.start();

const chain = await client.addChain({ chainSpec });

chain.sendJsonRpc(
  '{"jsonrpc":"2.0","id":1,"method":"system_name","params":[]}'
);

(async () => {
  while (true) {
    // Wait for a JSON-RPC response to come back. This is typically done in a loop in the background.
    console.log({ jsonRpcResponse: await chain.nextJsonRpcResponse() });
  }
})();

setTimeout(() => {
  console.log('will remove chain');
  // notice that when the chain is removed,
  // smoldot panics on chain.nextJsonRpcResponse()
  // see wasn-node Rust code
  // https://github.com/smol-dot/smoldot/blob/48864e7810746a55ba8aa7eb12156708f8630cc0/wasm-node/rust/src/lib.rs#L258
  chain.remove();
}, 10_000);

And the output is

[smoldot] Smoldot v1.0.15
[smoldot] Chain initialization complete for westend2. Name: "Westend". Genesis hash: 0xe143…423e. State root hash: 0x7e92439a94f79671f9cade9dff96a094519b9001a7432244d46ab644bb6f746f. Network identity: 12D3KooWA5qfvRuf5WncnAk2CANCsnBzSjwLVeEnX5Wzc5yTU2kd. Chain specification or database starting at: 0x1deb…95c7 (#16847280)
[json-rpc-westend2] The JSON-RPC client has just called a JSON-RPC function from the legacy JSON-RPC API (system_name). Legacy JSON-RPC functions have loose semantics and cannot be properly implemented on a light client. You are encouraged to use the new JSON-RPC API <https://github.com/paritytech/json-rpc-interface-spec/> instead. The legacy JSON-RPC API functions will be deprecated and removed in the distant future.
{
  jsonRpcResponse: '{"jsonrpc":"2.0","id":1,"result":"smoldot-light-wasm"}'
}
[sync-service-westend2] GrandPa warp sync finished to #17001662 (0xbfb4…753e)
[runtime-westend2] Finalized block runtime ready. Spec version: 9430. Size of `:code`: 1.2 MiB.
will remove chain
[smoldot] Shutting down chain westend2
Smoldot has panicked. This is a bug in smoldot. Please open an issue at https://github.com/smol-dot/smoldot/issues with the following message:
panicked at 'called `Option::unwrap()` on a `None` value', wasm-node/rust/src/lib.rs:258:10
Error
    at panic (/home/projects/smoldot-panic/node_modules/smoldot/dist/mjs/internals/local-instance.js:76:23)

The wasm-node rust code seems to be

smoldot/wasm-node/rust/src/lib.rs

Lines 253 to 258 in 48864e7

	fn json_rpc_responses_peek(chain_id: u32) -> u32 {
	let mut client_lock = CLIENT.lock().unwrap();
	match client_lock
	.chains
	.get_mut(usize::try_from(chain_id).unwrap())
	.unwrap()

I'm not sure if there is a better way to implement the loop to await for JSON RPC responses.