Vercel Edge Runtime Import or Module Error

1. Importing Node.js modules (fs, path, os) in middleware or edge functions
2. Using incompatible packages in edge functions (Prisma, heavy ORM, Node-specific crypto)
3. Dynamic imports or require() in edge runtime
4. Package dependencies not compatible with edge environment
5. Middleware importing from API routes that use Node.js modules

Avoid Node.js modules: Edge runtime is JavaScript only. Use browser APIs and lightweight npm packages.

Conditional imports: Use dynamic imports with runtime checks:
if (typeof window === 'undefined') { const fs = await import('fs') }

Use standard APIs: Replace fs with fetch, path with URL, crypto with subtle API.

Move logic: If need Node.js modules, move to API routes instead of middleware or edge functions.