fix initial value pass by reference error in executeFields in inner closure

Author: joonlabs

src/Execution/Executor.php

@@ -235,7 +235,7 @@ private function shouldIncludeNode(ExecutionContext $executionContext, $node): b
     public function executeFields(ExecutionContext $executionContext, GraphQLObjectType $parentType, $sourceValue, $path, $fields)
     {
         $initial = [];
-        return array_reduce(array_keys($fields), function (&$results, $responseName) use ($executionContext, $parentType, $sourceValue, $path, $fields) {
+        return array_reduce(array_keys($fields), function ($results, $responseName) use ($executionContext, $parentType, $sourceValue, $path, $fields) {
             $fieldNodes = $fields[$responseName];
             $fieldPath = [$path, $responseName, $parentType->getName()];