[CodingStyle] Handle null item on ManualJsonStringToJsonEncodeArrayRector

rules-tests/CodingStyle/Rector/Assign/ManualJsonStringToJsonEncodeArrayRector/Fixture/null_item.php.inc

@@ -0,0 +1,28 @@
+<?php
+
+namespace Rector\Tests\CodingStyle\Rector\Assign\ManualJsonStringToJsonEncodeArrayRector\Fixture;
+
+final class NullItem
+{
+    public function run()
+    {
+        $json = '{"a":null}';
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\CodingStyle\Rector\Assign\ManualJsonStringToJsonEncodeArrayRector\Fixture;
+
+final class NullItem
+{
+    public function run()
+    {
+        $jsonData = ['a' => null];
+        $json = \Nette\Utils\Json::encode($jsonData);
+    }
+}
+
+?>

src/PhpParser/Node/NodeFactory.php

@@ -595,7 +595,7 @@ private function createArrayItem($item, string | int | null $key = null): ArrayI
             $arrayItem = new ArrayItem($this->createArray($item));
         }
 
-        if ($item instanceof ClassConstFetch) {
+        if ($item === null || $item instanceof ClassConstFetch) {
             $itemValue = BuilderHelpers::normalizeValue($item);
             $arrayItem = new ArrayItem($itemValue);
         }