Pull request overview

Updates the localized Next.js App Router error page to optionally reveal underlying error information in non-production contexts, addressing missing diagnostics in Vercel Preview and local development (Fixes #7464).

Changes:

• Add a SHOW_ERROR_DETAILS environment-derived flag to gate error detail rendering.
• Render error message and digest in a <details> block on the localized 500 error page when the flag is enabled.
• Add a unit test to cover the “details visible” rendering path.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
apps/site/tests/errorPage.test.jsx	Adds a unit test asserting that technical details render when SHOW_ERROR_DETAILS is enabled.
apps/site/next.constants.mjs	Introduces SHOW_ERROR_DETAILS based on NODE_ENV and VERCEL_ENV.
apps/site/app/[locale]/error.tsx	Shows error message/digest in preview/dev via a gated <details> section.

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