File Upload to s3 bucket via NodeJS Console app via aws-sdk doesnt get completed

I do have a one time running JS file, which is running as a command line tool. But not as a REST server.

The issue I have is that I do have the following function which accepts the arguments and uploads a file to a specified S3 bucket.

const uploadToAWSS3Bucket = (stream, fileName, bucketName) =>{
    const params = {
        Bucket: bucketName || '',
        Key: fileName,
        Body: stream
    };

    console.log(`Using Bucket ${bucketName} for uploading the file ${fileName}`);
    
    return s3.upload(params, (err, data) => {
        if (err) {
            console.log(err);
        }
        console.log(data.stringify);
        console.log(`File uploaded successfully. ${data.Location}`);
        console.log(`Finished uploading the file ${fileName} to Bucket ${bucketName}.`);
        
    }).promise();
    // await sleep(80000);

};

This is called/implemented by the following method.

(async()=>{
    const result  = await uploadToAWSS3Bucket(stream, 'filename.json', 'mybucketname');
    console.log(result);           
});

However, the node index.js command exits with giving out a commandline output and it appears that the file upload never gets completed because of that.

Anything that I am missing or any trick that would work on this case?