Plugin is causing fatal error when you add product to cart.
PHP Fatal error: Uncaught Error: Cannot use object of type WP_Error as array in /home/xxx/public_html/wp-content/plugins/posturinn/inc/postis.class.php:394
Stack trace:
#0 /home/xxx/public_html/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-shipping-method.php(233): POSTIS_Shipping->calculate_shipping(Array)
#1 /home/xxx/public_html/wp-content/plugins/woocommerce/includes/class-wc-shipping.php(345): WC_Shipping_Method->get_rates_for_package(Array)
#2 /home/xxx/public_html/wp-content/plugins/woocommerce/includes/class-wc-shipping.php(260): WC_Shipping->calculate_shipping_for_package(Array, 0)
#3 /home/xxx/public_html/wp-content/plugins/woocommerce/includes/class-wc-cart.php(1391): WC_Shipping->calculate_shipping(Array)
#4 /home/xxx/public_html/wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(339): WC_Cart->calculate_shipping()
#5 /home/xxx/public_html/wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(849): WC_Cart_Totals->get_shipping_from_cart()
#6 /home/xxx in /home/xxx/public_html/wp-content/plugins/posturinn/inc/postis.class.php on line 394
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The placeholder attribute is missing in kennitala-field in this plugin. It should be placed here -> https://plugins.trac.www.ads-software.com/browser/posturinn/trunk/inc/checkout-fields.class.php#L41
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