Upgrade framework

vendor/nikic/php-parser/lib/PhpParser/NodeVisitorAbstract.php

@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace PhpParser;
 
@@ -7,8 +7,19 @@ namespace PhpParser;
  */
 class NodeVisitorAbstract implements NodeVisitor
 {
-    public function beforeTraverse(array $nodes)    { }
-    public function enterNode(Node $node) { }
-    public function leaveNode(Node $node) { }
-    public function afterTraverse(array $nodes)     { }
-}
+    public function beforeTraverse(array $nodes) {
+        return null;
+    }
+
+    public function enterNode(Node $node) {
+        return null;
+    }
+
+    public function leaveNode(Node $node) {
+        return null;
+    }
+
+    public function afterTraverse(array $nodes) {
+        return null;
+    }
+}