Update 'index.js'

index.js

@@ -16,7 +16,7 @@ const { messaging } = require("firebase-admin");
   admin.initializeApp(
     {
       credential: admin.credential.cert(adminAuthToken),
-      databaseURL: data.DB_URL,
+      databaseURL: process.env.DB_URL,
     },
     // key
   );