[Bug]: prod build marks worker export as not used

[felixmosh]

Version

System:
    OS: macOS 15.3.1
    CPU: (12) arm64 Apple M3 Pro
    Memory: 318.75 MB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Browsers:
    Chrome: 133.0.6943.127
    Safari: 18.3
  npmPackages:
    @rsbuild/core: ^1.2.8 => 1.2.11

Details

for some reason prod build marks the exported function as not used.

Reproduce link

https://github.com/felixmosh/rsbuild-worker-prod-bug

Reproduce Steps

1. yarn install
2. yarn dev - (check that all works, the worker prints worker content)
3. yarn build
4. node ./dist/server.js - fails since the exported variable is marked as unused (based on the comments)