[@vite/legacy] No worker file generate when using legacy to run vite build.

[Flcwl]

Describe the bug

I want to use the worker in old browser by @vite/legacy. But has no worker file generate when running vite build it.

import vue from '@vitejs/plugin-vue';
import legacy from '@vitejs/plugin-legacy';
import { resolve } from 'path';
import { defineConfig } from 'vite';

export default defineConfig({
  plugins: [
    vue(),
    legacy({
      renderModernChunks: false,
      renderLegacyChunks: true,
    }),
  ],
  build: {
    reportCompressedSize: false,
  },
  worker: {
    format: 'iife',
  },
  resolve: {
    alias: {
      '@': resolve(__dirname, './src'),
    },
  },
});

Reproduction

https://stackblitz.com/edit/node-la3to4sk?file=vite.config.ts

Steps to reproduce

Run npm install followed by npm run build

System Info

"devDependencies": {
    "@vitejs/plugin-legacy": "^6.0.0",
    "@vitejs/plugin-vue": "^5.2.1",
    "typescript": "^5.7.2",
    "vite": "^6.0.7"
  },

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

Duplicate of #18558