[FIX] missing Null Action

Modules/File/classes/class.ilObjFileGUI.php

@@ -271,7 +271,7 @@ public function executeCommand(): void
                 $action = match ($capability->getCapability()) {
                     Capabilities::VIEW_EXTERNAL => $this->action_repo->getViewActionForSuffix($suffix),
                     Capabilities::EDIT_EXTERNAL => $this->action_repo->getEditActionForSuffix($suffix),
-                    default => null
+                    default => $this->action_repo->null()
                 };
 
                 $this->tabs_gui->activateTab('content');

Services/WOPI/classes/Discovery/ActionDBRepository.php

@@ -47,6 +47,15 @@ private function implodeTargets(ActionTarget ...$targets): string
         );
     }
 
+    /**
+     * @description this is only for cases where you need an action (for compatibility), this action cannot be used
+     * for any WOPI capability
+     */
+    public function null(): NullAction
+    {
+        return new NullAction();
+    }
+
     public function hasActionForSuffix(
         string $suffix,
         ActionTarget ...$action_target

Services/WOPI/classes/Discovery/NullAction.php

@@ -0,0 +1,70 @@
+<?php
+
+/**
+ * This file is part of ILIAS, a powerful learning management system
+ * published by ILIAS open source e-Learning e.V.
+ *
+ * ILIAS is licensed with the GPL-3.0,
+ * see https://www.gnu.org/licenses/gpl-3.0.en.html
+ * You should have received a copy of said license along with the
+ * source code, too.
+ *
+ * If this is not the case or you just want to try ILIAS, you'll find
+ * us at:
+ * https://www.ilias.de
+ * https://github.com/ILIAS-eLearning
+ *
+ *********************************************************************/
+
+declare(strict_types=1);
+
+namespace ILIAS\Services\WOPI\Discovery;
+
+use ILIAS\Data\URI;
+
+/**
+ * @author Fabian Schmid <[email protected]>
+ */
+class NullAction extends Action
+{
+    /** @noinspection MagicMethodsValidityInspection */
+    public function __construct()
+    {
+    }
+
+    public function withId(int $id): self
+    {
+        return $this;
+    }
+
+    public function getId(): int
+    {
+        return 0;
+    }
+
+    public function getName(): string
+    {
+        return 'Null';
+    }
+
+    public function getExtension(): string
+    {
+        return '';
+    }
+
+    public function getLauncherUrl(): URI
+    {
+        return new URI(''); // this will fail, but a NullAction can't be used anyway
+    }
+
+    public function getUrlAppendix(): ?string
+    {
+        return null;
+    }
+
+    public function getTargetExtension(): ?string
+    {
+        return null;
+    }
+
+}