ErrorBoundary - process is not defined

[jezikk]

Reproduction

Reproduction repo: https://github.com/jezikk/rr-process-error

Reproduction steps:

1. Clone project.
2. Start project using pnpm dev.
3. Go to the main page.

Changes in code:

• Add .env file.
• Add a new function which throws 401 error
• Call this function in the loader of root
• Add process.env.TEST to ErrorBoundary component

System Info

System:
    OS: macOS 15.5
    CPU: (12) arm64 Apple M3 Pro
    Memory: 111.19 MB / 18.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.2.0 - /opt/homebrew/bin/node
    Yarn: 1.22.22 - /opt/homebrew/bin/yarn
    npm: 11.3.0 - /opt/homebrew/bin/npm
    pnpm: 9.15.4 - /opt/homebrew/bin/pnpm
  Browsers:
    Chrome: 138.0.7204.159
    Edge: 138.0.3351.95
    Safari: 18.5
  npmPackages:
    @react-router/dev: ^7.7.0 => 7.7.0
    @react-router/node: ^7.7.0 => 7.7.0
    @react-router/serve: ^7.7.0 => 7.7.0
    react-router: ^7.7.0 => 7.7.0
    vite: ^6.3.3 => 6.3.5

Used Package Manager

pnpm

Expected Behavior

It could be possible to render process.env environments in ErrorBoundary component.

Actual Behavior

ReferenceError: process is not defined
    at ErrorBoundary (http://localhost:5173/app/root.tsx:118:17)
    at react-stack-bottom-frame (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:17422:20)
    at renderWithHooks (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:4204:24)
    at updateFunctionComponent (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:6617:21)
    at beginWork (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:7652:20)
    at runWithFiberInDEV (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:1483:72)
    at performUnitOfWork (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:10866:98)
    at workLoopSync (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:10726:43)
    at renderRootSync (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:10709:13)
    at performWorkOnRoot (http://localhost:5173/node_modules/.vite/deps/react-dom_client.js?v=8098185c:10357:46)

[GabenGar]

It's not defined because the boundary rendered on client and process only exists in NodeJS runtime.
If you want to have some sort of env variable on server and client, then you must follow Vite's way of handling them.