Make $handleName nullable in afterAddHandle plugin

Author: peterjaap

Plugin/RemoveHandlersPlugin.php

@@ -24,7 +24,7 @@ public function __construct(
     public function afterAddHandle(
         ProcessorInterface $subject,
         ProcessorInterface $result,
-        array|string $handleName
+        array|string|null $handleName
     ): ProcessorInterface {
         if (!$this->config->isModuleEnabled()) {
             return $result;