nodejs aws s3 replace files

Im trying to upload a folder from a local directory to an AWS S3 Bucket.

I have the following code.

var s3 = require('s3');
var awsS3Client = new AWS.S3({
    accessKeyId: 'XXXXXXX',
    secretAccessKey: 'XXXXXXX'
});
var options = {
    s3Client: awsS3Client
};
var client = s3.createClient(options);

var params = {
    localDir: "./zips",
    deleteRemoved: true, // default false, whether to remove s3 objects
    // that have no corresponding local file.

    s3Params: {
        Bucket: "node-files",
        Prefix: "test/unzip/"
    },
};
var uploader = client.uploadDir(params);
uploader.on('error', function (err) {
    console.error("unable to sync:", err.stack);
});
uploader.on('progress', function () {
    console.log("progress", uploader.progressAmount, uploader.progressTotal);
});
uploader.on('end', function () {
    console.log("done uploading");
});

All works fine when uploading for the first time, the directory and all of its files are in tact and in the bucket.

However when i try a second time, the buffer just gets stuck and times out.

Im assuming i either need to set some kind of option to overwrite the existing files?