Fixed missing event manager for form AssetEditForm.

application/config/module.config.php

@@ -519,6 +519,7 @@
             Form\Initializer\Csrf::class,
         ],
         'factories' => [
+            'Omeka\Form\AssetEditForm' => Service\Form\FormWithEventManagerFactory::class,
             'Omeka\Form\ResourceForm' => Service\Form\ResourceFormFactory::class,
             'Omeka\Form\VocabularyForm' => Service\Form\VocabularyFormFactory::class,
             'Omeka\Form\ResourceBatchUpdateForm' => Service\Form\ResourceBatchUpdateFormFactory::class,

application/src/Service/Form/FormWithEventManagerFactory.php

@@ -0,0 +1,16 @@
+<?php declare(strict_types=1);
+
+namespace Omeka\Service\Form;
+
+use Interop\Container\ContainerInterface;
+use Laminas\ServiceManager\Factory\FactoryInterface;
+
+class FormWithEventManagerFactory implements FactoryInterface
+{
+    public function __invoke(ContainerInterface $services, $requestedName, array $options = null)
+    {
+        $form = new $requestedName(null, $options ?? []);
+        $form->setEventManager($services->get('EventManager'));
+        return $form;
+    }
+}