Allow that the DEFAULT_URI does not end with a slash

We normalize the url with an env var processor before passing it to the saml lib, to avoid an error. Fixes issue #1118

src/EnvVarProcessors/AddSlashEnvVarProcessor.php

@@ -0,0 +1,49 @@
+<?php
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2025 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  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/>.
+ */
+
+declare(strict_types=1);
+
+
+namespace App\EnvVarProcessors;
+
+use Symfony\Component\DependencyInjection\EnvVarProcessorInterface;
+
+/**
+ * Env var processor that adds a trailing slash to a string if not already present.
+ */
+final class AddSlashEnvVarProcessor implements EnvVarProcessorInterface
+{
+
+    public function getEnv(string $prefix, string $name, \Closure $getEnv): mixed
+    {
+        $env = $getEnv($name);
+        if (!is_string($env)) {
+            throw new \InvalidArgumentException(sprintf('The "addSlash" env var processor only works with strings, got %s.', gettype($env)));
+        }
+        return rtrim($env, '/') . '/';
+    }
+
+    public static function getProvidedTypes(): array
+    {
+        return [
+            'addSlash' => 'string',
+        ];
+    }
+}

src/EnvVarProcessors/CustomEnvVarProcessor.php

@@ -20,7 +20,7 @@
 
 declare(strict_types=1);
 
-namespace App\Services;
+namespace App\EnvVarProcessors;
 
 use Closure;
 use Symfony\Component\DependencyInjection\EnvVarProcessorInterface;