Shadow: ⚗️ Add Nuxt error tracking (v5)

[allspain]

Shadow Review — PR #4477 v5

Source: DataDog/browser-sdk#4477
Commit: b13420280c15615b1f0f5cd317725b7fec5cb743
Timestamp: 2026-04-20T07:45:14Z

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Original PR Description

Motivation

This PR adds first-class Nuxt error tracking, covering both Vue rendering/lifecycle errors (via vueApp.config.errorHandler) and Nuxt startup errors thrown in plugins or app hooks (via the app:error hook).

Changes

New public APIs (exported from @datadog/browser-rum-nuxt)

• addNuxtError(error, instance, info) — a low-level function compatible with both vueApp.config.errorHandler and Nuxt's app:error hook. Intended for users who want manual control. It:

  • Captures a handling stack at call time
  • Builds a component stack string from the Vue component hierarchy and the info string
  • Merges a dd_context property from the error object (if present) into the event context
  • Tags all events with framework: 'nuxt'
  • Buffers errors thrown before RUM initialises and flushes them once datadogRum.init completes

• setupNuxtErrorHandling(nuxtApp) — a convenience helper that sets up both handlers automatically. It:

  • Wraps the existing vueApp.config.errorHandler (preserving Nuxt's own error page handler)
  • Hooks into app:error for errors thrown during plugin/app startup
  • Uses WeakSet-based deduplication to prevent double-reporting when the same error bubbles through both errorHandler and app:error

Internal changes

• nuxtRumPlugin now implements the onRumStart lifecycle hook to receive and distribute the addError function to buffered subscribers
• createHandlingStack extended with a 'nuxt error' source label

Test instructions

1. Unit tests:

   yarn test:unit --spec packages/rum-nuxt/src/domain/error/addNuxtError.spec.ts

2. E2E tests:

   yarn test:e2e:init
   yarn test:e2e -g "nuxt error"

3. Manual:

   • Start the Nuxt test app and navigate to /error-test. Click "Trigger Error" and verify a single RUM error event is collected with error.source: custom, context.framework: nuxt, and a handling_stack.
   • Navigate to /startup-error and verify a single RUM error event is collected for the startup error thrown in the plugin, again with context.framework: nuxt and a handling_stack.

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file