Fix dumping callables on Node::__toString()

src/Node/Node.php

@@ -54,7 +54,7 @@ class Node implements \Countable, \IteratorAggregate
     {
         $attributes = [];
         foreach ($this->attributes as $name => $value) {
-            $attributes[] = \sprintf('%s: %s', $name, str_replace("\n", '', var_export($value, true)));
+            $attributes[] = \sprintf('%s: %s', $name, is_callable($value) ? '\Closure' : str_replace("\n", '', var_export($value, true)));
         }
 
         $repr = [static::class.'('.implode(', ', $attributes)];

tests/Node/NodeTest.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Twig\Tests\Node;
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use PHPUnit\Framework\TestCase;
+use Twig\Node\Node;
+
+class NodeTest extends TestCase
+{
+    public function testToString()
+    {
+        // callable is not a supported type for a Node attribute, but Drupal uses some apparently
+        $node = new Node([], ['value' => function () { return '1'; }], 1);
+
+        $this->assertEquals('Twig\Node\Node(value: \Closure)', (string) $node);
+    }
+}