Error on product update

Problem/Motivation

With the Mailchimp Ecommerce Ecommerce submodule installed, an error occurs when saving products.

Steps to reproduce

• Install Mailchimp Ecommerce and the Ecommerce submodule on an existing site with products.
• Edit and save a product (either through the UI or programmatically)
• Resulting error in the error log is: Uncaught PHP Exception Error: "Call to a member function buildProductVariants() on null" at /opt/drupal/web/modules/contrib/mailchimp_ecommerce/modules/mailchimp_ecommerce_commerce/src/EventSubscriber/ProductEventSubscriber.php line 62

I have installed 2.x-dev on a dev server and tested on one a copy of the site and the issue no longer seems to occur. We don't really want to install that version on production servers, when is the next release likely to be?