Receiving a TypeError from AccountForm when using multistep for anonymous user registration

Problem/Motivation

We're using simple_multistep for user registration of new users; the registration has 3 steps.

Following the change in https://git.drupalcode.org/project/simple_multistep/-/commit/cdb6a11a13e..., we are now seeing a TypeError after submitting step 2:

TypeError: key(): Argument #1 ($array) must be of type array, null given in key() (line 362 of core/modules/user/src/AccountForm.php).

Steps to reproduce

1. Install the latest 8.x-1.x-dev version of the module
2. Use simple_multistep for user registration
3. Create at least three steps for user registration
4. Attempt to go through user registration

I notice in FormStep.php, it seems like name, pass, and mail are specifically added to step values if it sees account -- I believe that roles should be added to this list.