Forbid adding Nodes to EmptyNode

src/Node/EmptyNode.php

@@ -25,4 +25,9 @@ final class EmptyNode extends Node
     {
         parent::__construct([], [], $lineno);
     }
+
+    public function setNode(string $name, Node $node): void
+    {
+        throw new \LogicException('EmptyNode cannot have children.');
+    }
 }

src/Node/ModuleNode.php

@@ -44,11 +44,11 @@ final class ModuleNode extends Node
             'blocks' => $blocks,
             'macros' => $macros,
             'traits' => $traits,
-            'display_start' => new EmptyNode(),
-            'display_end' => new EmptyNode(),
-            'constructor_start' => new EmptyNode(),
-            'constructor_end' => new EmptyNode(),
-            'class_end' => new EmptyNode(),
+            'display_start' => new Nodes(),
+            'display_end' => new Nodes(),
+            'constructor_start' => new Nodes(),
+            'constructor_end' => new Nodes(),
+            'class_end' => new Nodes(),
         ];
         if (null !== $parent) {
             $nodes['parent'] = $parent;