The patch is attached. Looks like it was just that the tweener library
was moved rather than removed.
https://github.com/pixel-saver/pixel-saver/commit/cceefae50cf85f725385c492d756f4e3257473b7.patch
>From cceefae50cf85f725385c492d756f4e3257473b7 Mon Sep 17 00:00:00 2001
From: Pellegrino Prevete <pellegrinoprev...@gmail.com>
Date: Thu, 1 Oct 2020 15:49:03 +0200
Subject: [PATCH] remove Tweener Shell dependency for 3.38 support
---
pixel-sa...@deadalnix.me/app_menu.js | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/pixel-sa...@deadalnix.me/app_menu.js b/pixel-sa...@deadalnix.me/app_menu.js
index 51efd4c..138e29d 100644
--- a/pixel-sa...@deadalnix.me/app_menu.js
+++ b/pixel-sa...@deadalnix.me/app_menu.js
@@ -3,7 +3,7 @@ const Main = imports.ui.main;
const Mainloop = imports.mainloop;
const Shell = imports.gi.Shell;
const St = imports.gi.St;
-const Tweener = imports.ui.tweener;
+const Tweener = imports.tweener.tweener;
const ExtensionUtils = imports.misc.extensionUtils;
const Me = ExtensionUtils.getCurrentExtension();
