Describe the bug

From this pr which cause process.env.FOO is undefined in nodejs environment and we must use process.env['FOO'] to get the right value because process.env will be replaced with ({})

Reproduction

$ git clone git@github.com:zhangyuang/vite-ssr-error-require.git
$ git checkout bug/env

System Info

$ npx envinfo --system --npmPackages '{vite,@vitejs/*}' --binaries --browsers

  System:
    OS: macOS 10.15.4
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Memory: 278.79 MB / 16.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 14.17.2 - ~/.nvm/versions/node/v14.17.2/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 7.17.0 - /usr/local/bin/npm
  Browsers:
    Chrome: 95.0.4638.54
    Safari: 13.1
  npmPackages:
    @vitejs/plugin-vue: ^1.0.0 => 1.9.3
    @vitejs/plugin-vue-jsx: ^1.0.0 => 1.2.0
    vite: ^2.6.11 => 2.6.11

Used Package Manager

yarn

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 https://github.com/vuejs/vue-next instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.