downgrade to kirby v3

kirby/src/Http/Request/Files.php

@@ -21,17 +21,25 @@ class Files
 
 	/**
 	 * Sanitized array of all received files
+	 *
+	 * @var array
 	 */
-	protected array $files = [];
+	protected $files;
 
 	/**
 	 * Creates a new Files object
 	 * Pass your own array to mock
 	 * uploads.
+	 *
+	 * @param array|null $files
 	 */
-	public function __construct(array|null $files = null)
+	public function __construct($files = null)
 	{
-		$files ??= $_FILES;
+		if ($files === null) {
+			$files = $_FILES;
+		}
+
+		$this->files = [];
 
 		foreach ($files as $key => $file) {
 			if (is_array($file['name'])) {
@@ -55,6 +63,8 @@ class Files
 	 * array. This is only needed to make
 	 * the Data trait work for the Files::get($key)
 	 * method.
+	 *
+	 * @return array
 	 */
 	public function data(): array
 	{