Merx comes with English and German error messages. If you want to translate or overwrite these messages you can do so by setting the translations keys in your languages file.

Keys are prefixed with error.merx..

Key	English
initializePayment	The payment could not be initialized.
noPaymentMethod	No payment method provided.
fieldsvalidation	Field validation failed.
emptycart	Cart is empty.
completePayment	The payment could not be completed.
paymentCanceled	You canceled the payment.
cart.add	Item "{id}" could not be added to cart.
cart.update	Cart items could not be updated.
order.changeNum	Sorting number of a complete order cannot be changed.
order.changeStatus	Status of a complete order cannot be changed.

site/languages/de.php

return [
  'code' => 'de',
  'direction' => 'ltr',
  'locale' => 'de_DE',
  'name' => 'Schwäbisch',
  'translations' => [
    'error.merx.emptycart' => 'Du hasch gar koine Produkte im Körble.',
  ]
];