fix: PHP8 test error when constructing Mage_Core_Model_Config

The constructor of Mage_Core_Model_Config inherits from Varien_Object and its first argument is written to $this->data. So when the "constructor" of Mage_Core_Model_Config kicks in, it wanted to write an array to a already populated $this->_data variable, which yields errors since PHP 7.1.

app/code/core/Mage/Core/Helper/EnvironmentConfigLoader.php

@@ -50,10 +50,10 @@ class Mage_Core_Helper_EnvironmentConfigLoader extends Mage_Core_Helper_Abstract
      * Override the store 'german' configuration:
      * @example OPENMAGE_CONFIG__STORES__GERMAN__GENERAL__STORE_INFORMATION__NAME=store_german
      *
-     * @param Mage_Core_Model_Config $xmlConfig
+     * @param Varien_Simplexml_Config $xmlConfig
      * @return void
      */
-    public function overrideEnvironment(Mage_Core_Model_Config $xmlConfig)
+    public function overrideEnvironment(Varien_Simplexml_Config $xmlConfig)
     {
         $env = $this->getEnv();
 

dev/tests/unit/Mage/Core/Helper/EnvironmentConfigLoaderTest.php

@@ -41,13 +41,12 @@ public function testBuildNodePath()
      */
     public function testEnvOverrides(array $config)
     {
-        error_reporting(0);
         $xmlStruct = $this->getTestXml();
 
-        $xmlDefault = new Mage_Core_Model_Config($xmlStruct);
-        $xmlDefault = $xmlDefault->loadModulesConfiguration('config.xml', $xmlDefault);
-        $xml = new Mage_Core_Model_Config($xmlStruct);
-        $xml = $xml->loadModulesConfiguration('config.xml', $xml);
+        $xmlDefault = new \Varien_Simplexml_Config();
+        $xmlDefault->loadString($xmlStruct);
+        $xml = new \Varien_Simplexml_Config();
+        $xml->loadString($xmlStruct);
 
         $this->assertEquals('test_default', (string)$xml->getNode('default/general/store_information/name'));
         $this->assertEquals('test_website', (string)$xml->getNode('websites/base/general/store_information/name'));