Fix type inspection for app.root service

Author: tstoeckler

src/Type/ServiceDynamicReturnTypeExtension.php

@@ -55,6 +55,12 @@ public function getTypeFromMethodCall(
         if ($methodReflection->getName() === 'get') {
             $service = $this->serviceMap->getService($serviceId);
             if ($service instanceof DrupalServiceDefinition) {
+                // Work around Drupal misusing the SplString class for string
+                // pseudo-services such as 'app.root'.
+                // @see https://www.drupal.org/project/drupal/issues/3074585
+                if ($service->getClass() === 'SplString') {
+                    return new StringType();
+                }
                 return new ObjectType($service->getClass() ?? $serviceId);
             }
             return $returnType;