Add throws annotation

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/private/legacy/app.php

@@ -257,6 +257,7 @@ class OC_App {
 	 * Load app.php from the given app
 	 *
 	 * @param string $app app name
+	 * @throws Error
 	 */
 	private static function requireAppFile($app) {
 		// encapsulated here to avoid variable scope conflicts