fix

src/lib/firebase.ts

@@ -0,0 +1,15 @@
+import { initializeApp, getApps } from 'firebase/app';
+import { getMessaging, getToken, onMessage, isSupported } from 'firebase/messaging';
+
+const firebaseConfig = {
+  apiKey: process.env.NEXT_PUBLIC_FIREBASE_API_KEY,
+  authDomain: process.env.NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN,
+  projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
+  storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
+  messagingSenderId: process.env.NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID,
+  appId: process.env.NEXT_PUBLIC_FIREBASE_APP_ID,
+};
+
+const app = getApps().length === 0 ? initializeApp(firebaseConfig) : getApps()[0];
+
+export { app, getMessaging, getToken, onMessage, isSupported };