Module Federation remote errors aren't symbolicated by the host dev server

[MikitasK]

Describe the bug

Errors thrown inside Module Federation remote aren't correctly symbolicated by the host dev server.

React Native shows the generated remote bundle location instead of the original source file. dev server reports:

Failed to symbolicate {
  error: 'Source map for __federation_expose_MiniAppNavigator.chunk.bundle for ios is missing'
}

this affects both iOS & Android

System Info

@callstack/repack: 5.3.0 workspace version
@callstack/repack-dev-server: 5.3.0 workspace version
react-native: 0.86.0
react: 19.2.8
@module-federation/enhanced: 2.8.0
rspack: 1.6.0
webpack: 5.105.x
node.js: 25.9.0
pnpm: 10.34.5

Re.Pack Version

4.3.0

Reproduction

https://github.com/callstack/repack/tree/main/apps/tester-federation-v2

Steps to reproduce

mf_errors_symbolication.mp4

1. add some error inside the mini app. for example in src/mini/screens/GalleryScreen.tsx

throw new Error('MINI APP ERROR');

2. start the host & mini-app servers:

pnpm --filter tester-federation-v2 start:hostapp
pnpm --filter tester-federation-v2 start:miniapp

3. run the app:

pnpm --filter tester-federation-v2 ios
pnpm --filter tester-federation-v2 android

4. Navigate to the mini app

Actual behavior

• stack frame points to __federation_expose_MiniAppNavigator.chunk.bundle
• host dev server reports that source map is missing
• original source frame is unavailable or may point to incorrect host file with the same filename

Expected behavior

• stack frame should resolve to the original mini-app source file
• RN error overlay should display correct source code frame
• pressing the frame should open corresponding mini-app file in IDE