App crashes silently when using fetch() inside worklet runtime

[enlob]

Description

When calling fetch() inside a worklet runtime created with react-native-worklets, the app crashes immediately without printing any error messages to the console. This makes it impossible to debug what's going wrong.

The documentation suggests that fetch() is supported in worklets - as shown in the official React Native Worklets introduction video at 1:07:

However, attempting to use fetch() as demonstrated causes an immediate crash.

Steps to reproduce

1. Clone the reproduction repository: https://github.com/enlob/react-native-worklets-fetch
2. Install dependencies: npm install
3. Run on device: npx expo run:android or npx expo run:ios
4. App crashes immediately on load

Snack or a link to a repository

https://github.com/enlob/react-native-worklets-fetch

Reanimated version

~4.1.1

Worklets version

0.6.1

React Native version

0.81.5

Platforms

Android

JavaScript runtime

Hermes

Workflow

Expo Dev Client

Architecture

New Architecture (Fabric renderer)

Reanimated feature flags

None

React Native release level

None

Build type

No response

Device

Real device

Host machine

Windows

Device model

No response

Acknowledgements

Yes

[tjzel]

Hi @enlob! Sorry to disappoint you but the screen was coming from a still work-in-progress PR #8410 and isn't yet available on stable releases.

The feature itself requires the Bundle Mode enabled and I decided to postpone it until it's unblocked by Meta.

[enlob]

Hi @tjzel, will it work if I apply the patches as described here?

[tjzel]

Unfortunately not yet. I plan to release experimental fetch on iOS with the Bundle Mode by the end of the year but I can't guarantee the timeline on that.

[enlob]

Ok good to know. I'll be looking forward to that!