drupal_root must be defined in the container - parametersSchema requires it

Author: ondrejmirtes

extension.neon

@@ -12,13 +12,14 @@ parameters:
 		- profile
 		- engine
 	drupal:
+		drupal_root: null
 		entityTypeStorageMapping:
 			node: Drupal\node\NodeStorage
 			taxonomy_term: Drupal\taxonomy\TermStorage
 			user: Drupal\user\UserStorage
 parametersSchema:
 	drupal: structure([
-		drupal_root: string()
+		drupal_root: schema(string(), nullable())
 		entityTypeStorageMapping: arrayOf(string())
 	])
 rules:

src/Drupal/DrupalAutoloader.php

@@ -63,8 +63,8 @@ class DrupalAutoloader
     public function register(Container $container): void
     {
         $startPath = null;
-        $drupalParams = $container->hasParameter('drupal') ? $container->getParameter('drupal') : [
-          'drupal_root' => null,
+        $drupalParams = [
+          'drupal_root' => $container->getParameter('drupal'),
           'serviceMap' => [],
           'entityTypeStorageMapping' => [],
         ];