[TypeDeclaration] Handle crash on no namespace with + operation on DeclareStrictTypesRector

rules-tests/TypeDeclaration/Rector/StmtsAwareInterface/DeclareStrictTypesRector/Fixture/no_namespace_with_plus_operation.php.inc

@@ -0,0 +1,27 @@
+<?php
+
+final class NoNamespaceWithOperationPlusOperation
+{
+    private array $prop2;
+
+    public function resolve2(array $second)
+    {
+        return $this->prop2 + $second;
+    }
+}
+
+?>
+-----
+<?php
+
+declare(strict_types=1);
+
+final class NoNamespaceWithOperationPlusOperation
+{
+    private array $prop2;
+
+    public function resolve2(array $second)
+    {
+        return $this->prop2 + $second;
+    }
+}

rules/TypeDeclaration/Rector/StmtsAwareInterface/DeclareStrictTypesRector.php

@@ -62,11 +62,14 @@ public function beforeTraverse(array $nodes): ?array
         $stmt = current($newStmts);
 
         if ($stmt instanceof FileWithoutNamespace) {
-            $stmt = current($stmt->stmts);
+            $currentStmt = current($stmt->stmts);
 
-            if (! $stmt instanceof Stmt) {
+            if (! $currentStmt instanceof Stmt) {
                 return null;
             }
+
+            $nodes = $stmt->stmts;
+            $stmt = $currentStmt;
         }
 
         // when first stmt is Declare_, verify if there is strict_types definition already,