Describe the bug

The generated worker file contains es syntax
export function __vite_legacy_guard()

Cannot be used normally in worker

Reproduction

https://stackblitz.com/edit/vitejs-vite-ixsfq5p1?file=main.js

Steps to reproduce

1.npm install
2.npm run build

System Info

System:
    OS: Windows 10 10.0.19042
    CPU: (6) x64 Intel(R) Core(TM) i5-9400F CPU @ 2.90GHz
    Memory: 3.29 GB / 15.95 GB
  Binaries:
    Node: 20.11.0 - E:\Program Files\nodejs\node.EXE
    npm: 10.2.4 - E:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.19041.1266.0), Chromium (127.0.2651.74)
    Internet Explorer: 11.0.19041.1566
  npmPackages:
    @vitejs/plugin-legacy: ^6.0.0 => 6.0.0 
    @vitejs/plugin-react: ^4.3.4 => 4.3.4 
    vite: ^6.0.3 => 6.0.3

Used Package Manager

npm

Logs

No response

Validations

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• The provided reproduction is a minimal reproducible example of the bug.