fix: Forking world state in prover-node (#7995)

Attempt to fix the `Error in prover node work: Error No such file or
directory` error in prover-node when forking. Tested by connecting to
the container, modifying the js, and running prover-node manually.

---------

Co-authored-by: PhilWindle <philip.windle@gmail.com>

yarn-project/kv-store/src/lmdb/store.test.ts

@@ -20,11 +20,16 @@ describe('AztecLmdbStore', () => {
   };
 
   it('forks a persistent store', async () => {
-    const path = join(await mkdtemp(join(tmpdir(), 'aztec-store-test-')), 'main.mdb');
+    const path = await mkdtemp(join(tmpdir(), 'aztec-store-test-'));
     const store = AztecLmdbStore.open(path, false);
     await itForks(store);
   });
 
+  it('forks a persistent store with no path', async () => {
+    const store = AztecLmdbStore.open(undefined, false);
+    await itForks(store);
+  });
+
   it('forks an ephemeral store', async () => {
     const store = AztecLmdbStore.open(undefined, true);
     await itForks(store);

yarn-project/kv-store/src/lmdb/store.ts

@@ -72,7 +72,8 @@ export class AztecLmdbStore implements AztecKVStore {
   async fork() {
     const baseDir = this.path ? dirname(this.path) : tmpdir();
     this.#log.debug(`Forking store with basedir ${baseDir}`);
-    const forkPath = join(await mkdtemp(join(baseDir, 'aztec-store-fork-')), 'root.mdb');
+    const forkPath =
+      (await mkdtemp(join(baseDir, 'aztec-store-fork-'))) + (this.isEphemeral || !this.path ? '/data.mdb' : '');
     this.#log.verbose(`Forking store to ${forkPath}`);
     await this.#rootDb.backup(forkPath, false);
     const forkDb = open(forkPath, { noSync: this.isEphemeral });