Fix initial root hierarchy creation

Author: sneakyvv

src/TwigComponent/src/ComponentRenderer.php

@@ -118,8 +118,8 @@ private function preRender(MountedComponent $mounted, array $context = []): PreR
         $component = $mounted->getComponent();
 
         // add the "parent" component when rendering a nested embedded component
-        if (isset($context[PreRenderEvent::EMBEDDED]) && true === $context[PreRenderEvent::EMBEDDED]) {
-            $hierarchy = isset($context['this']) && $context['this'] instanceof Hierarchy ? $context['this'] : new Hierarchy($component);
+        if (isset($context[PreRenderEvent::EMBEDDED]) && true === $context[PreRenderEvent::EMBEDDED] && isset($context['this'])) {
+            $hierarchy = $context['this'] instanceof Hierarchy ? $context['this'] : new Hierarchy($context['this']);
             if (isset($context['this'])) {
                 $hierarchy = $hierarchy->add($component);
             }

src/TwigComponent/tests/Integration/EmbeddedComponentTest.php

@@ -150,9 +150,9 @@ public function testBlockDefinitionCanAccessTheContextOfTheDestinationBlocks():
         );
     }
 
-    public function testAccessingTheHierarchyToHighThrowsAnException(): void
+    public function testAccessingTheHierarchyTooHighThrowsAnException(): void
     {
-        $this->expectExceptionMessage('Impossible to access an attribute ("foo") on a null variable');
+        $this->expectExceptionMessage('Neither the property "parent" nor one of the methods "parent()", "getparent()"/"isparent()"/"hasparent()" or "__call()" exist');
         self::getContainer()->get(Environment::class)->render('embedded_component_hierarchy_exception.html.twig');
     }