Magento 2: eccezione dell'osservatore di eventi non visualizzata sullo schermo

Nell'estensione personalizzata, creo un osservatore come questo.

app\code\Vendor\Extension\etc\frontend\events.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="sales_quote_remove_item">
    <observer name="sales_quote_remove_item_handler" instance="Vendor\Extension\Observer\RemovecartbeforeObserver" shared="false" />
  </event>
</config>

E il mio osservatore:

app\code\Vendor\Extension\Observer\RemovecartbeforeObserver.php

use Magento\Framework\Event\ObserverInterface;

class RemovecartbeforeObserver implements ObserverInterface
{
   public function execute(\Magento\Framework\Event\Observer $observer)
   {
       // HERE IS MY CODE
       $message = "THIS IS CUSTOM ERROR MESSAGE";
       throw new \Magento\Framework\Exception\LocalizedException(__($message));
       return;
    }
 }

La funzione My Observer viene chiamata, ma non mostra errori personalizzati nella pagina. A parte questo, mostra il mio messaggio in un exception.logfile come questo.

main.CRITICAL: exception 'Magento\Framework\Exception\LocalizedException' with message 'THIS IS CUSTOM ERROR MESSAGE' in E:\xampp\htdocs\myworks\magento213\app\code\Vendor\Extension\Observer\RemovecartbeforeObserver.php:106 

Guarda come mostra il messaggio predefinito.

Cerco altre cose su questo e alla fine ho trovato la mia soluzione,

Devo solo cambiare il codice dell'osservatore in questo modo.

app\code\Vendor\Extension\Observer\RemovecartbeforeObserver.php

use Magento\Framework\Event\ObserverInterface;

class RemovecartbeforeObserver implements ObserverInterface
{
   protected $messageManager;
   protected $_responseFactory;
   protected $_url;

    public function __construct(\Magento\Framework\Message\ManagerInterface $messageManager,
    \Magento\Framework\App\ResponseFactory $responseFactory,
    \Magento\Framework\UrlInterface $url)
   {
       $this->messageManager = $messageManager;
       $this->_responseFactory = $responseFactory;
       $this->_url = $url;
   }

   public function execute(\Magento\Framework\Event\Observer $observer)
   {
       // HERE IS MY CODE
       $message = "THIS IS CUSTOM ERROR MESSAGE";
       $this->messageManager->addError($message);
       $cartUrl = $this->_url->getUrl('checkout/cart/index');
       $this->_responseFactory->create()->setRedirect($cartUrl)->sendResponse();            
       exit;
    }
 }

Aggiorna la tua classe in modo che sia così:

use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\Event\Observer;
use Magento\Framework\Message\ManagerInterface as MessageManagerInterface;
use Magento\Framework\Controller\Result\RedirectFactory;

class RemovecartbeforeObserver implements ObserverInterface
{
    protected $messageManager;
    protected $redirectFactory;

    public function __construct(
        MessageManagerInterface $messageManager,
        RedirectFactory $redirectFactory
    ) {
        $this->messageManager = $messageManager;
        $this->redirectFactory = $redirectFactory;
    }

    public function execute(Observer $observer)
    {
        $observer->getRequest()->setParam('item', false);

        $message = "THIS IS CUSTOM ERROR MESSAGE";
        $this->messageManager->addError($message);

        return $this->redirectFactory->create()->setPath('*/*/');
    }
}