Getting ENOENT error when deploying a function for the notifications of my application (Firebase function)

Question

I'm trying to deploy a function to send notifications for my chat application. I get this error shown below, but I can't understand where the it comes from.

Could you help me to understand where the error comes from? Is this a problem with my code in the index.js file?

Here is the error:

index.js :

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

exports.notifyNewMessage = functions.firestore
        .document('notifications/{uId}/messages/{messageId}')
        .onCreate( async (docSnapshot, context) => {
            //************************************Obtener datos de la notificacion
            const messageNotification = docSnapshot.data();
            ////////////extraemos los datos
            const uidAuthor = messageNotification['uidAuthor'];
            const uidReceiver = messageNotification['uidReceiver'];
            const messages = messageNotification['message'];
            const typeNotification = messageNotification['type'];
        
            //************************************DECLARAR PROMESAS
            const getAuthorData = admin.firestore().doc('users/' + uidAuthor).get();
            const getReceiverData = admin.firestore().doc('users/' + uidReceiver).get();
            //************************************
            const results = await Promise.all([getAuthorData, getReceiverData]);
            //************************************
            const author = results[0];
            const receiver = results[1];
            //************************************GET DATA USER AUTHOR
            const name = author.get('name');
            //************************************GET DATA USER RECEIVER
            const tokenNotification = receiver.get('tokenNotification');
            //console.log("Datos recogidos USER TO NOTIFY:TOKENS " + tokens);
 
            //////////////////////////////////NOTIFICATION DATA
    
            payload = {
                data: {
                    typeNotif: typeNotification.toString(),
                    userName: name,
                    userID: uidAuthor,
                    message: messages
                }
            };
    
            admin.messaging().sendToDevice(tokenNotification, payload)
              .then(function(response) {
               
                   return response;
                })
              .catch(function(error) {
              
                   return error;
                });
              
            //////////////////////////////////
});

firebase.js:

{
  "functions": {
    "predeploy": [
      "npm --prefix functions run lint" 
    ]
  }
}