Allow build without DATABASE_URL; only require it at runtime

src/lib/db.ts

@@ -2,11 +2,29 @@ import { Pool } from 'pg';
 
 const connectionString = process.env.DATABASE_URL;
 
-if (!connectionString) {
-  throw new Error('DATABASE_URL environment variable is not set');
+function createPool() {
+  if (!connectionString) {
+    if (process.env.NODE_ENV === 'production') {
+      throw new Error('DATABASE_URL environment variable is not set');
+    }
+    // During build we don't need a real connection; return a stubbed pool
+    // that throws clearly if someone actually tries to query.
+    return {
+      query: async () => {
+        throw new Error('DATABASE_URL environment variable is not set');
+      },
+      connect: async () => {
+        throw new Error('DATABASE_URL environment variable is not set');
+      },
+      end: async () => {},
+      on: () => {},
+      removeListener: () => {},
+    } as unknown as Pool;
+  }
+  return new Pool({ connectionString });
 }
 
-export const db = new Pool({ connectionString });
+export const db = createPool();
 
 export async function query(text: string, params?: unknown[]) {
   const result = await db.query(text, params);