Storybook with builder-webpac5 complains about conflicting values in DefinePlugin and not redefine custom variables

Describe the bug I am using Storybook6-rc01 with builder-webpack5. I define several variables with patching webpack config and DefinePlugin through function webpackFinal:

plugins: [
      new webpack.DefinePlugin({
      "process.env.NODE_ENV": JSON.stringify("development"),
      "window.FAKE_GLOBAL_FUNCTION": "(function() { return false; })",
    }),
],

Function FAKE_GLOBAL_FUNCTION call is added to test story

But there is error about Conflicting values for 'process.env' in build console and there is error on rendered story on UI about window.FAKE_GLOBAL_FUNCTION is not defined

To Reproduce Steps to reproduce the behavior:

1. Go to https://github.com/khats/storybook-demo
2. Pull project
3. Install dependencies with yarn
4. Start storybook with yarn start-storybook

Expected behavior

1. No error in build console: Conflicting values for 'process.env' '{NODE_ENV: "development", NODE_PATH: [], STORYBOOK: "true", PUBLIC_URL: "."}' !== '{}'
2. window. FAKE_GLOBAL_FUNCTION is defined and story is rendered without error

Screenshots

Code snippets If applicable, add code samples to help explain your problem.

System Environment Info:

System: OS: macOS 11.0.1 CPU: (12) x64 Intel® Core™ i7-9750H CPU @ 2.60GHz Binaries: Node: 14.15.3 - ~/.nvm/versions/node/v14.15.3/bin/node Yarn: 2.4.0 - /usr/local/bin/yarn npm: 6.14.9 - ~/.nvm/versions/node/v14.15.3/bin/npm Browsers: Chrome: 89.0.4389.90 Firefox: 76.0.1 Safari: 14.0.1

Additional context Add any other context about the problem here.

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[WodenWang820118]

Hi, any update regarding this issue? Storybook version: 6.5.9 I am using Angular 13 with @storybook/angular and @storybook/builder-webpack5 without any manually added plugin, but how should I fix it? Thanks.

[azangru]

Still seeing “Conflicting values for process.env” 😞 . Upgraded from 6.2.9 to 6.3.4: