Webpack: preload-only entries overwrite renderer URL defines #4454

Pre-flight checklist

• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project uses.
• I have searched the issue tracker for a bug that matches the one I want to file, without success.

Forge version

7.8.1

Electron version

44.9.1

Operating system

macOS 26.7.1 arm64

Last known working Forge version

No response

Expected behavior

MAIN_WINDOW_WEBPACK_ENTRY resolves to main_window/index.html, regardless of group order.

Actual behavior

A preload-only entry overwrites it with main_window/index.js, although that entry builds no renderer script. This then loads JavaScript instead of HTML:

window.loadURL(MAIN_WINDOW_WEBPACK_ENTRY);

Steps to reproduce

Configure separate renderer groups for a page and a preload-only entry with the same name, placing the preload group last:

renderer: [
  {
    config: {
      optimization: {
        splitChunks: { chunks: 'all', minChunks: 2 },
      },
    },
    entryPoints: [
      {
        name: 'main_window',
        html: './src/index.html',
        js: './src/renderer.js',
      },
    ],
  },
  {
    config: {},
    entryPoints: [
      {
        name: 'main_window',
        preload: { js: './src/preload.js' },
      },
    ],
  },
],

Additional information

Separate groups allow page scripts to share chunks while keeping preloads self-contained. At present, they must be ordered with the page group last to produce the correct URL.