fix(render): new ErrorBoundary breaking rendering in server components

[gabrielmfern]

We were getting this error at https://react.email when rendering components because the new ErrorBoundary approach to avoid client side rendering fallback was using React class components, which doesn't work in Server Components

⨯ TypeError: Class extends value undefined is not a constructor or null

This might be caused by a React Class Component being rendered in a Server Component, React Class Components only works in Client Components. Read more: https://nextjs.org/docs/messages/class-component-in-server-component
     at createErrorBoundary (../../packages/render/src/shared/error-boundary.tsx:7:46)
    at <unknown> (../../packages/render/src/node/render.tsx:22:29)

We could define a separate export for react-server, but it also so happens React.Component is undefined in server environments, and we can just check for that.

---

Summary by cubic

Fixes server component rendering by making ErrorBoundary safe in React Server Components. Adds a guard for React.Component and falls back to a pass-through boundary so pages render without crashing.

• Bug Fixes
  • Check if React.Component is defined; if not, return a no-op boundary that renders children.
  • Keep class-based ErrorBoundary for client components.
  • Prevents internal server errors seen on react.email.

^{Written for commit 423dd5e. Summary will update on new commits.}

[changeset-bot]

🦋 Changeset detected

Latest commit: 423dd5e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@react-email/render	Patch
@react-email/components	Patch
playground	Patch

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Project	Deployment	Review	Updated (UTC)
react-email	Ready	Preview, Comment	Jan 20, 2026 1:12pm
react-email-demo	Ready	Preview, Comment	Jan 20, 2026 1:12pm

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npm i https://pkg.pr.new/resend/react-email/@react-email/render@2871

commit: 423dd5e

[cubic-dev-ai]

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