Shopify Add-to-Cart Error Fix

When a visitor clicks the “Add to Cart” button on my homepage, an error message pops up and nothing is added. The same products can still be added from the catalogue and individual product pages, so the issue is clearly tied to the homepage section or its AJAX call... (Budget: $10 - $30 USD, Jobs: AJAX, CSS, Debugging, HTML, JavaScript, PHP, Shopify, Web Development)