diff --git a/lib/PhpParser/NodeTraverser.php b/lib/PhpParser/NodeTraverser.php
index c6fc1574ab..0d81aedb37 100644
--- a/lib/PhpParser/NodeTraverser.php
+++ b/lib/PhpParser/NodeTraverser.php
@@ -201,10 +201,10 @@ protected function traverseArray(array $nodes): array {
                         if ($return instanceof Node) {
                             $this->ensureReplacementReasonable($node, $return);
                             $node = $return;
-                        } else if (\is_array($return)) {
+                        } elseif (\is_array($return)) {
                             $doNodes[] = [$i, $return];
                             continue 2;
-                        } else if (self::REMOVE_NODE === $return) {
+                        } elseif (self::REMOVE_NODE === $return) {
                             $doNodes[] = [$i, []];
                             continue 2;
                         } elseif (self::DONT_TRAVERSE_CHILDREN === $return) {
diff --git a/tools/composer.json b/tools/composer.json
new file mode 100644
index 0000000000..d263715f3f
--- /dev/null
+++ b/tools/composer.json
@@ -0,0 +1,6 @@
+{
+    "require": {
+        "friendsofphp/php-cs-fixer": "^3.10",
+        "phpstan/phpstan": "^1.8"
+    }
+}