fix: build issue

Author: DuttaNeel07

lib/db.ts

@@ -2,10 +2,6 @@ import mongoose from 'mongoose';
 
 const MONGODB_URI = process.env.MONGODB_URI;
 
-if (!MONGODB_URI) {
-    throw new Error('Please define the MONGODB_URI environment variable inside .env.local');
-}
-
 interface MongooseCache {
     conn: mongoose.Connection | null;
     promise: Promise<mongoose.Connection> | null;
@@ -22,6 +18,10 @@ if (!cached) {
 }
 
 async function dbConnect() {
+    if (!MONGODB_URI) {
+        throw new Error('Please define the MONGODB_URI environment variable inside .env.local');
+    }
+
     if (cached.conn) {
         return cached.conn;
     }