🎯 Goal

Fix a race condition crash that occurs when onNext is called on a subscription that has already been disposed:

Fatal Exception: java.lang.IllegalStateException: Subscription already disposed, onNext should not be called on it
at io.getstream.chat.android.client.utils.observable.SubscriptionImpl.onNext(Subscriptions.kt:52)

The crash happens due to a TOCTOU (time-of-check to time-of-use) race condition between:

1. ChatEventsObservable.notifySubscriptions() checking subscription.isDisposed → returns false
2. Another thread calling subscription.dispose() → sets isDisposed = true
3. notifySubscriptions() calling subscription.onNext(event) → check(!isDisposed) throws

🛠 Implementation details

• Replace check(!isDisposed) with if (isDisposed) return in both SubscriptionImpl and SuspendSubscription
• This handles the race condition gracefully by returning early instead of crashing
• The listener?.onEvent() safe call provides additional safety if listener becomes null mid-execution
• Updated tests to verify the new behavior (no exception, listener not called when disposed)

🎨 UI Changes

No UI changes.

🧪 Testing

• Unit tests updated and passing
• The race condition is inherently difficult to reproduce, but the fix ensures that even if the race occurs, the app won't crash

Summary by CodeRabbit

• Bug Fixes
  • Fixed crash when onNext is called on a disposed subscription. The app now gracefully handles this scenario instead of throwing an exception.