Current Behavior

Running nx build <project> --configuration=development with @nx/rspack causes this error:

TypeError: Cannot read properties of undefined (reading 'removeAvailableModules')

Expected Behavior

The development build should succeed using Rspack with default settings, even if the "optimization" field is omitted from the dev config.

GitHub Repo

https://github.com/CuriousSyrup/nx-rspack-dev-bug

Steps to Reproduce

1. Create workspace
   npx create-nx-workspace nx-node-lib-rspack
cd nx-node-lib-rspack

2. Add node + rspack plugins
   npx nx add @nx/node
npx nx g @nx/node:lib libs/node-lib --useProjectJson
npx nx add @nx/rspack

3. Create libs/node-lib/rspack.config.js with:

const { join } = require('path');
const { NxAppRspackPlugin } = require('@nx/rspack/app-plugin');

module.exports = {
  entry: './src/index.ts',
  output: {
    path: join(__dirname, 'dist'),
  },
  plugins: [
    new NxAppRspackPlugin({
      target: 'node',
      tsConfig: './tsconfig.lib.json',
      main: './src/index.ts',
      progress: true,
    }),
  ],
};

4. In libs/node-lib/project.json, set configurations:

{
  "build": {
    "executor": "@nx/rspack:rspack",
    "options": {
      "main": "libs/node-lib/src/index.ts",
      "rspackConfig": "libs/node-lib/rspack.config.js",
      "outputPath": "dist"
    },
    "defaultConfiguration": "production",
    "configurations": {
      "development": {
        "mode": "development"
      },
      "production": {
        "mode": "production",
        "optimization": true,
        "sourceMap": false
      }
    }
  }
}

5. Run builds
   nx build node-lib --configuration=production # ✅ works
   nx build node-lib --configuration=development # ❌ crashes

Nx Report

Node           : 22.14.0
OS             : linux-x64
Native Target  : x86_64-linux
npm            : 10.9.2

nx                     : 21.0.3
@nx/js                 : 21.0.3
@nx/jest               : 21.0.3
@nx/eslint             : 21.0.3
@nx/workspace          : 21.0.3
@nx/devkit             : 21.0.3
@nx/module-federation  : 21.0.3
@nx/node               : 21.0.3
@nx/rspack             : 21.0.3
@nx/web                : 21.0.3
typescript             : 5.7.3
---------------------------------------
Registered Plugins:
@nx/js/typescript
@nx/rspack/plugin
---------------------------------------
Cache Usage: 0.00 B / 182.38 GB

Failure Logs

> nx run @nx-test/node-lib:build:development


 NX   Cannot read properties of undefined (reading 'removeAvailableModules')

Package Manager Version

No response

Operating System

• macOS
• Linux
• Windows
• Other (Please specify)

Additional Information

No response