Analytics initializes only on the client side

Analytics SDKs reach for window, document, and localStorage during initialization. When that code runs inside a React Server Component or at module top-level in an SSR file, the server throws ReferenceError: window is not defined and the page either 500s or renders a broken shell. Users see a white screen; crawlers see an error; Vercel logs fill with the same stack trace. The analytics tool you installed to observe the site is actively preventing it from rendering.

Move all SDK initialization into a component marked 'use client' and wrap the call in useEffect(() => { initializeAnalytics() }, []) so it runs only after hydration. For script-tag analytics like GA4 or GTM, use Next.js <Script strategy="afterInteractive"> which defers loading until the client is ready. See components/analytics-provider.tsx as the single initialization site.