fix: Race condition while unwinding blocks

yarn-project/archiver/src/archiver/archiver_store_test_suite.ts

@@ -8,6 +8,7 @@ import { times, timesParallel } from '@aztec/foundation/collection';
 import { randomInt } from '@aztec/foundation/crypto';
 import { Signature } from '@aztec/foundation/eth-signature';
 import { Fr } from '@aztec/foundation/fields';
+import { sleep } from '@aztec/foundation/sleep';
 import { AztecAddress } from '@aztec/stdlib/aztec-address';
 import { L2Block, wrapInBlock } from '@aztec/stdlib/block';
 import {
@@ -254,6 +255,20 @@ export function describeArchiverDataStore(
       it('returns undefined if tx is not found', async () => {
         await expect(store.getTxEffect(TxHash.random())).resolves.toBeUndefined();
       });
+
+      it('does not fail if the block is unwound while requesting a tx', async () => {
+        const expectedTx = await wrapInBlock(blocks[1].block.body.txEffects[0], blocks[1].block);
+        let done = false;
+        void (async () => {
+          while (!done) {
+            void store.getTxEffect(expectedTx.data.txHash);
+            await sleep(1);
+          }
+        })();
+        await store.unwindBlocks(blocks.length, blocks.length);
+        done = true;
+        expect(await store.getTxEffect(expectedTx.data.txHash)).toEqual(undefined);
+      });
     });
 
     describe('L1 to L2 Messages', () => {

yarn-project/archiver/src/archiver/kv_archiver_store/block_store.ts

@@ -131,7 +131,10 @@ export class BlockStore {
    */
   async *getBlocks(start: number, limit: number): AsyncIterableIterator<PublishedL2Block> {
     for await (const blockStorage of this.#blocks.valuesAsync(this.#computeBlockRange(start, limit))) {
-      yield await this.getBlockFromBlockStorage(blockStorage);
+      const block = await this.getBlockFromBlockStorage(blockStorage);
+      if (block) {
+        yield block;
+      }
     }
   }
 
@@ -166,9 +169,8 @@ export class BlockStore {
     const blockHash = (await header.hash()).toString();
     const blockBodyBuffer = await this.#blockBodies.getAsync(blockHash);
     if (blockBodyBuffer === undefined) {
-      throw new Error(
-        `Could not retrieve body for block ${header.globalVariables.blockNumber.toNumber()} ${blockHash}`,
-      );
+      this.#log.warn(`Could not find body for block ${header.globalVariables.blockNumber.toNumber()} ${blockHash}`);
+      return undefined;
     }
     const body = Body.fromBuffer(blockBodyBuffer);
     const block = new L2Block(archive, header, body);
@@ -210,7 +212,11 @@ export class BlockStore {
       return undefined;
     }
 
-    const block = (await this.getBlock(blockNumber))!;
+    const block = await this.getBlock(blockNumber);
+    if (!block) {
+      return undefined;
+    }
+
     const tx = block.block.body.txEffects[txIndex];
 
     return new TxReceipt(