Cloud Function

I have been trying to deploy cloud function but it always fails. I tried to deploy a simple cloud function but it is not working and can not find any error too. and I am in Blaze plan

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

// Firestore collection to listen to
const collectionName = 'testCollection';

exports.logNewDocument = functions.firestore
  .document(`${collectionName}/{documentId}`)
  .onCreate((snapshot) => {
    const newValue = snapshot.data();

    // Log the new document's data
    console.log(`New document added to ${collectionName}:`, newValue);

    return null;
  });