bug: iOS swift concurrency EXC_BAD_ACCESS in Firestore addCollectionSnapshotListener

[TomCarey]

Plugin(s)

• Analytics
• App
• App Check
• Authentication
• Crashlytics
• Cloud Firestore
• Cloud Functions
• Cloud Messaging
• Cloud Storage
• Performance
• Remote Config

Version

6.2.0

Platform(s)

• Android
• iOS
• Web

Current behavior

When calling FirebaseFirestore.addCollectionSnapshotListener in a useEffect that appropriately removes the snapshot listener when unmounting I sometimes get a crash in the iOS plugin FirebaseFirestore.swift:244 where there is a bad access due to a concurrent write on a dictionary that isn't thread safe.

Expected behavior

It should not crash. It should ensure all read/write operations are performed in a thread-safe manor.

Reproduction

https://github.com/capawesome-team/.capacitor-app

Steps to reproduce

Sorry, I don't have capacity to set this up in an example since it doesn't always happen (threading race condition)

Other information

I have a fix ready to be turned into a PR that manages the listenerRegistrationMap by wrapping it with an actor

Capacitor doctor

This isn't relevant

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