From 914fb89a4ae1128d8525e9038b80e1169801a16c Mon Sep 17 00:00:00 2001
From: Pierre Krieger <pierre.krieger1708@gmail.com>
Date: Sat, 23 Dec 2023 12:31:57 +0100
Subject: [PATCH] Fix JavaScript error when a JSON-RPC response is generated
 while a chain is removed (#1512)

* Fix bug

* CHANGELOG
---
 wasm-node/CHANGELOG.md                                | 1 +
 wasm-node/javascript/src/internals/remote-instance.ts | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/wasm-node/CHANGELOG.md b/wasm-node/CHANGELOG.md
index 247d82c00a..ecc27b022b 100644
--- a/wasm-node/CHANGELOG.md
+++ b/wasm-node/CHANGELOG.md
@@ -12,6 +12,7 @@
 - Fix state mismatch during warp syncing if a peer sends a bad header, justification, or proof. ([#1498](https://github.com/smol-dot/smoldot/pull/1498))
 - Fix bugs in various corner cases when decoding and analyzing a Merkle proof. ([#1462](https://github.com/smol-dot/smoldot/pull/1462))
 - Fix Merkle proofs being considered as invalid if they contain a storage value that happens to successfully decode as a trie node with an inline child. ([#1504](https://github.com/smol-dot/smoldot/pull/1504))
+- Fix crash when using a worker due to race condition when a chain is removed while a JSON-RPC response is generated for it. ([#1512](https://github.com/smol-dot/smoldot/pull/1512))
 
 ## 2.0.15 - 2023-12-20
 
diff --git a/wasm-node/javascript/src/internals/remote-instance.ts b/wasm-node/javascript/src/internals/remote-instance.ts
index 52e48a14f5..5b66f5e892 100644
--- a/wasm-node/javascript/src/internals/remote-instance.ts
+++ b/wasm-node/javascript/src/internals/remote-instance.ts
@@ -147,9 +147,10 @@ export async function connectToInstanceServer(config: ConnectConfig): Promise<in
             case "json-rpc-response": {
                 const queue = state.jsonRpcResponses.get(message.chainId);
                 // The chain might have been removed locally in the past.
-                if (queue)
+                if (queue) {
                     queue.push(message.response);
                     config.eventCallback({ ty: "json-rpc-responses-non-empty", chainId: message.chainId })
+                }
                 return;
             }
         }