feat(auth0-server-js): export TokenExchangeError from public surface

[cschetan77]

Summary

• Re-exports TokenExchangeError and MissingClientAuthError from @auth0/auth0-auth-js in the auth0-server-js public surface
• Both loginWithCustomTokenExchange() and customTokenExchange() are documented as throwing these errors, but consumers had no way to import them from @auth0/auth0-server-js — they were forced to reach into @auth0/auth0-auth-js directly (a transitive dependency) or fall back to matching on error.name
• TokenExchangeError: thrown when the exchange fails (bad subject token, Auth0 rejects the request, validation errors)
• MissingClientAuthError: thrown when the client is not configured with a clientSecret or clientAssertionSigningKey — CTE requires a confidential client
• Framework SDKs built on top of auth0-server-js (e.g. auth0-fastify) can now re-export both errors cleanly without adding auth0-auth-js as a direct dependency
• Follows the same pattern as TokenResponse and ActClaim added in feat(auth0-server-js): export TokenResponse and ActClaim types #194

[coderabbitai]

📝 Walkthrough

Walkthrough

A single line is added to packages/auth0-server-js/src/index.ts to re-export TokenExchangeError from @auth0/auth0-auth-js, making the error type directly importable from the auth0-server-js package.

Changes

TokenExchangeError Public Export

Layer / File(s)	Summary
Re-export TokenExchangeError in package index packages/auth0-server-js/src/index.ts	Adds TokenExchangeError re-export from @auth0/auth0-auth-js to the public surface of auth0-server-js.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Possibly related PRs

• auth0/auth0-auth-js#176: Introduces Custom Token Exchange methods and tests that rely on TokenExchangeError being surfaced on exchange failures — directly motivating this re-export.

Suggested reviewers

• nandan-bhat

Poem

A tiny line, a single re-export so neat,
🐇 The rabbit hops and says, "Now errors are complete!"
TokenExchangeError leaps into the light,
No hidden imports needed — all in plain sight.
One line of code, yet perfectly right! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly and clearly describes the main change: exporting TokenExchangeError from the public API surface of auth0-server-js.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/export-token-exchange-error

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}