Fix race condition in session transactions

ts/SignalProtocolStore.ts

@@ -625,10 +625,21 @@ export class SignalProtocolStore extends EventsMixin {
       window.log.info(
         `${debugName}: locked by ${this.currentZone.name}, waiting`
       );
-      await new Promise<void>(resolve => this.zoneQueue.push(resolve));
 
-      const duration = Date.now() - start;
-      window.log.info(`${debugName}: unlocked after ${duration}ms`);
+      return new Promise<T>((resolve, reject) => {
+        this.zoneQueue.push(async () => {
+          const duration = Date.now() - start;
+          window.log.info(`${debugName}: unlocked after ${duration}ms`);
+
+          // Call `.withZone` synchronously from `this.zoneQueue` to avoid
+          // extra in-between ticks while we are on microtasks queue.
+          try {
+            resolve(await this.withZone(zone, name, body));
+          } catch (error) {
+            reject(error);
+          }
+        });
+      });
     }
 
     this.enterZone(zone, name);

ts/test-electron/SignalProtocolStore_test.ts

@@ -1384,6 +1384,32 @@ describe('SignalProtocolStore', () => {
 
       assert.equal(await store.loadSession(id), testRecord);
     });
+
+    it('can be re-entered after waiting', async () => {
+      const a = new Zone('a');
+      const b = new Zone('b');
+
+      const order: Array<number> = [];
+      const promises: Array<Promise<unknown>> = [];
+
+      // What happens below is briefly following:
+      // 1. We enter zone "a"
+      // 2. We wait for zone "a" to be left to enter zone "b"
+      // 3. Skip few ticks to trigger leave of zone "a" and resolve the waiting
+      //    queue promise for zone "b"
+      // 4. Enter zone "a" while resolution was the promise above is queued in
+      //    microtasks queue.
+
+      promises.push(store.withZone(a, 'a', async () => order.push(1)));
+      promises.push(store.withZone(b, 'b', async () => order.push(2)));
+      await Promise.resolve();
+      await Promise.resolve();
+      promises.push(store.withZone(a, 'a again', async () => order.push(3)));
+
+      await Promise.all(promises);
+
+      assert.deepEqual(order, [1, 2, 3]);
+    });
   });
 
   describe('Not yet processed messages', () => {