FrontController.php

<?php
// Put here: override/classes/controller/FrontController.php

class FrontController extends FrontControllerCore
{
	public function display()
	{
		Media::addJsDef(array(
			'str_lang_impossible_add_to_cart' => Tools::displayError('Impossible to add the product to the cart.'),
			'str_lang_error_unable_to_delete_product' => Tools::displayError('ERROR: unable to delete the product.'),
			'str_lang_technical_error' => Tools::displayError('TECHNICAL ERROR:'),
			'str_lang_details' => Tools::displayError('Details:'),
			'str_lang_error_thrown' => Tools::displayError('Error thrown:'),
			'str_lang_text_status' => Tools::displayError('Text status:'),
			'str_lang_response_text' => Tools::displayError('Response text:'),
		));
		parent::display();
	}
}