Fix phpstan errors

Author: pierlon

lib/optimizer/src/TransformationEngine.php

@@ -112,12 +112,15 @@ private function getTransformerDependencies($transformerClass)
 
         $dependencies = [];
         foreach ($constructor->getParameters() as $parameter) {
+            $dependencyType = null;
+
             // The use of `ReflectionParameter::getClass()` is deprecated in PHP 8, and is superseded
             // by `ReflectionParameter::getType()`. See https://github.com/php/php-src/pull/5209.
-            if (version_compare('7.0', PHP_VERSION, '<')) {
+            if (version_compare('7.1', PHP_VERSION, '<')) {
                 if ($parameter->getType()) {
-                    $dependencyName = $parameter->getType()->getName();
-                    $dependencyType = new ReflectionClass($dependencyName);
+                    /** @var \ReflectionNamedType $returnType */
+                    $returnType = $parameter->getType();
+                    $dependencyType = new ReflectionClass($returnType->getName());
                 }
             } else {
                 $dependencyType = $parameter->getClass();