Error Packaging Function

I write a simple function that will render a simple view but every time I save the function it throws an error saying "Error Packaging Function. Please try again or contact support for assistance." and I'm pretty sure that I created a working manifest. Any idea to make this function works?

P.S.: Please look at my simple function below

'use strict';

const handler = (event, context, callback) => {
    let strHTMLResponse = `
    <html>
        <head>
        </head>
        <body>
            <h1> Hi </h1>
        </body>
    </html>
    `;

    callback(null, { eventResponse: strHTMLResponse });
};

exports.handler = handler;