[Bug]: Error: Loading PostCSS Plugin failed: The URL must be of scheme file

[intellild]

Version

System:
    OS: macOS 15.7.4
    CPU: (10) arm64 Apple M1 Max
    Memory: 11.60 GB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Browsers:
    Chrome: 146.0.7680.178
    Firefox: 148.0
    Safari: 26.3
  npmPackages:
    @modern-js/app-tools: 3.1.2 => 3.1.2
    @modern-js/runtime: 3.1.2 => 3.1.2
    @modern-js/tsconfig: 3.1.2 => 3.1.2

Details

modernjs-test@0.1.0 dev /Volumes/code/modernjs-test
modern dev

Modern.js Framework v3.1.2

error Error: Loading PostCSS Plugin failed: The URL must be of scheme file

(@/Volumes/code/modernjs-test/postcss.config.mjs)
at load (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:574:23)
at async Promise.all (index 0)
at async plugins (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:579:231)
at async processResult (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:482:26)
at async getPostcssLoaderOptions (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:4519:42)
at async Object.handler (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:8358:52)
at async Object.callChain (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:2667:30)
at async modifyBundlerChain (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:3756:64)
at async generateRspackConfig (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:3918:122)
at async initConfigs_initConfigs (file:///Volumes/code/modernjs-test/node_modules/.pnpm/@rsbuild+core@2.0.0-rc.0_@emnapi+core@1.9.2_@emnapi+runtime@1.9.2_core-js@3.49.0/node_modules/@rsbuild/core/dist/552.js:4062:108)

### Reproduce link

https://github.com/intellild/modernjs-v3-tailwind-crash

### Reproduce Steps

1. create a new modern.js v3 project
2. add tailwind to project
```shell
pnpm add tailwindcss @tailwindcss/postcss -D

postcss.config.mjs

export default {
  plugins: {
    '@tailwindcss/postcss': {}
  }
};

3. runpnpm dev

[intellild]

Seams to be a rsbuild issue. I am verifying it.

[intellild]

newly created rsbuild 2.0.0-beta.0 project works fine with tailwind 4.2.2

[intellild]

modern.js 3.0.5 works with tailwind 4.2.2

[GiveMe-A-Name]

Have any reproduce repo ?

[intellild]

Have any reproduce repo ?

@GiveMe-A-Name

crash with modern.js 3.1.2
https://github.com/intellild/modernjs-v3-tailwind-crash