Catch exception when invalid country_id is submitted in estimate ship… (#4427)

* Catch exception when invalid country_id is submitted in estimate shipping action. Fixes #4417

* phpstan

---------

Co-authored-by: Sven Reichel <github-sr@hotmail.com>

Author: colinmollenhour

.phpstan.dist.baseline.neon

@@ -3415,11 +3415,6 @@ parameters:
 			count: 2
 			path: app/code/core/Mage/Directory/Model/Observer.php
 
-		-
-			message: "#^Parameter \\#2 \\$countryId of method Mage_Directory_Model_Resource_Region\\:\\:_loadByCountry\\(\\) expects int, string given\\.$#"
-			count: 2
-			path: app/code/core/Mage/Directory/Model/Resource/Region.php
-
 		-
 			message: "#^Left side of && is always true\\.$#"
 			count: 1

app/code/core/Mage/Checkout/controllers/CartController.php

@@ -533,6 +533,14 @@ public function estimatePostAction()
         $regionId   = (string) $this->getRequest()->getParam('region_id');
         $region     = (string) $this->getRequest()->getParam('region');
 
+        try {
+            Mage::getModel('directory/country')->loadByCode($country);
+        } catch (Mage_Core_Exception $e) {
+            $this->_getSession()->addError($e->getMessage());
+            $this->_goBack();
+            return;
+        }
+
         $this->_getQuote()->getShippingAddress()
             ->setCountryId($country)
             ->setCity($city)

app/code/core/Mage/Directory/Model/Resource/Region.php

@@ -84,7 +84,7 @@ protected function _getLoadSelect($field, $value, $object)
      * Load object by country id and code or default name
      *
      * @param Mage_Core_Model_Abstract $object
-     * @param int $countryId
+     * @param string $countryId
      * @param string $value
      * @param string $field
      *