Handle errors

A failed request rejects with a plain object carrying a code, not an Error.

Read the error code
try {
  await subbly.cart.addItem({ productId: 3301 })
} catch (error) {
  if (error.code === 'out_of_stock') {
    // tell the customer
  }
}

The full list of codes is on the Subbly.js SDK reference.