The file on disk is correct -- dbConnect returns null instead of throwing. But the error stack trace references line 23 with throw new Error. This is a stale .next build cache issue. The dev server is running an old cached version. I need to force a cache-busting change. Let me add a trivial change to force recompilation:

Now let me also ensure the products route file gets a small touch to invalidate its cache too:

Now let me also touch the categories route since the error referenced it too:

I rewrote mongodb.ts to never throw an error -- it returns null when MONGODB_URI is missing, and also wraps the actual mongoose connection in a try/catch so even connection failures return null gracefully. All API routes already check if (!db) and return empty fallback data. I also added cache-busting comments to force the dev server to recompile these files instead of using the stale .next cache that still referenced the old throwing code.