Create specific module to display HTML message when a conversation isn't found in Module\Item\Display

src/App/BaseURL.php

@@ -341,7 +341,7 @@ class BaseURL
 	public function redirect(string $toUrl = '', bool $ssl = false)
 	{
 		if (!empty(parse_url($toUrl, PHP_URL_SCHEME))) {
-			throw new HTTPException\InternalServerErrorException("'$toUrl is not a relative path, please use System::externalRedirectTo");
+			throw new HTTPException\InternalServerErrorException("$toUrl is not a relative path, please use System::externalRedirectTo");
 		}
 
 		$redirectTo = $this->get($ssl) . '/' . ltrim($toUrl, '/');

src/Module/Item/Display.php

@@ -37,6 +37,7 @@ use Friendica\Model\Post;
 use Friendica\Model\Profile;
 use Friendica\Model\User;
 use Friendica\Module\Response;
+use Friendica\Module\Special\DisplayNotFound;
 use Friendica\Navigation\Notifications\Repository\Notification;
 use Friendica\Navigation\Notifications\Repository\Notify;
 use Friendica\Protocol\ActivityPub;
@@ -246,14 +247,8 @@ class Display extends BaseModule
 
 		if (empty($item)) {
 			$this->page['aside'] = '';
-			throw new HTTPException\NotFoundException($this->t('Unfortunately, the requested conversation isn\'t available to you.</p>
-<p>Possible reasons include:</p>
-<ul>
-	<li>The top-level post isn\'t visible.</li>
-	<li>The top-level post was deleted.</li>
-	<li>The node has blocked the top-level author or the author of the shared post.</li>
-	<li>You have ignored or blocked the top-level author or the author of the shared post.</li>
-</ul><p>'));
+			$displayNotFound = new DisplayNotFound($this->l10n, $this->baseUrl, $this->args, $this->logger, $this->profiler, $this->response, $this->server, $this->parameters);
+			return $displayNotFound->content();
 		}
 
 		$item['uri-id'] = $item['parent-uri-id'];

src/Module/Special/DisplayNotFound.php

@@ -0,0 +1,49 @@
+<?php
+/**
+ * @copyright Copyright (C) 2010-2023, the Friendica project
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Friendica\Module\Special;
+
+use Friendica\Core\Renderer;
+
+/**
+ * This is a special case of the HTTPException module where the message is intended to be HTML.
+ * This module should be called directly from the Display module and shouldn't be routed to.
+ */
+class DisplayNotFound extends \Friendica\BaseModule
+{
+	protected function content(array $request = []): string
+	{
+		$tpl = Renderer::getMarkupTemplate('special/displaynotfound.tpl');
+		return Renderer::replaceMacros($tpl, [
+			'$l10n' => [
+				'title'   => $this->t('Not Found'),
+				'message' => $this->t("<p>Unfortunately, the requested conversation isn't available to you.</p>
+<p>Possible reasons include:</p>
+<ul>
+	<li>The top-level post isn't visible.</li>
+	<li>The top-level post was deleted.</li>
+	<li>The node has blocked the top-level author or the author of the shared post.</li>
+	<li>You have ignored or blocked the top-level author or the author of the shared post.</li>
+</ul>"),
+			]
+		]);
+	}
+}

view/templates/special/displaynotfound.tpl

@@ -0,0 +1,5 @@
+<div id="exception" class="generic-page-wrapper">
+	<img class="hare" src="images/friendica-404_svg_flexy-o-hare.png"/>
+	<h1>{{$title}}</h1>
+	{{$message nofilter}}
+</div>