We've downloaded and inspected your error log and there are no ATUM-related errors since 24th September 2018.
Almost all the recent errors you have there are related to an outdated gateway plugin (Klarna Checkout for WooCommerce). I'd recommend you to update all your plugins to the latest versions to avoid deprecated issues like this one.
That said, Might you describe us what is wrong with ATUM + Product bundles, please?
- What does mean that Stock Central stopped working? Do you mean that is not loading at all?
- How did you reach the conclusion that is related to Product Bundles?
- Are you using the latest version of Product Bundles?