Estoy tratando de usar funciones en la nube para hacer una función programada en la nube de pub sub en nodjs, pero tengo dificultades para llamar a la función porque cada vez que compilo el código aparece este error

 Error: Failed to load function definition from source: Failed to generate manifest from function source: ReferenceError: Cannot access 'sendNotifications' before initialization

¿Cuál es la forma correcta en que debo agregar la función de notificación de envío en mi programador de pub sub?

 // The Cloud Functions for Firebase SDK to create Cloud Functions and set up triggers. const functions = require('firebase-functions'); const express = require('express'); const app = express(); const bodyParser = require('body-parser'); const cookieParser = require('cookie-parser'); const cors = require('cors'); const errorHandler = require('./_middleware/error-handler'); // The Firebase Admin SDK to access Firestore. const admin = require('firebase-admin'); admin.initializeApp(); const sendNotifications = require('./notifications.controller') // Create an Express object and routes (in order) app.use(bodyParser.urlencoded({ extended: false })); app.use(bodyParser.json()); app.use(cookieParser()); // allow cors requests from any origin app.use(cors()); // api routes app.use('/', require('./invites.controller')); app.use('/', require('.//payments.controller')); // INVITE PAGE app.get('/invite/:inviteId', function(request, response) { response.sendFile(__dirname + '/download.html'); }); // global error handler app.use(errorHandler); // Set our GCF handler to our Express app. exports.invites = functions.region('europe-west2').https.onRequest(app); exports.payments = functions.region('europe-west2').https.onRequest(app); exports.notificationScheduler = functions.pubsub .schedule('0 8 * * *') .timeZone('Europe/London') .onRun(async() => { await sendNotifications() });