TypeError when starting donation process

If you have your site configured for Option 2 (standard checkout) as you stated in 💬 Donation checkout flow not being displayed in config Active then the /donate route isn't going to work. That's the beginning of a dedicated checkout process that only does donations.

I changed my setup to "Allow both". I also decided to uninstall and reinstall, in case something got "twisted up" during my original setup.

Here's what I've got:

/admin/commerce/config/donation-settings

"Allow both" is selected

Configuration for /donate route: 
OrderItem to use on /donate: Donation

Order to use with the OrderItem chosen above: Default
(I did create a new Order type called "Donation", but if I select it here and save, the setting simply reverts back to "Default". Bug? See the red arrows.)

Checkout Flow: Donation Flow

Configuration for /cart route: 
OrderItem to use with /cart | /checkout: Default

Order to use with the OrderItem chosen above: Default

Checkout flow: Default

I notice that the "both" configuration scenario states:

"You will need to create extensions of the donation and memorial panes that select for your additional OrderItem type, and use those panes in the checkout flow which you configure to use this second OrderItem."

What specific action do I need to take to do that? Or is that already done by way of me moving the "Add a Donation" item to the first step of the Donation Order Flow?

Thank you!

"You will need to create extensions of the donation and memorial panes that select for your additional OrderItem type, and use those panes in the checkout flow which you configure to use this second OrderItem."

The included checkout panes, regardless of which setup is used, look for donation OrderItems. Using both checkout routes is an advanced scenario that requires having a second OrderItem type created and then coding checkout panes to look for that type. This can be done by extending the existing pane plugins but the module does not currently offer out of the box for this scenario.

I'm not sure I follow. Installation of the module auto-created a "donation" Order Item Type. Are you saying I need to create an additional Order Item Type, for example "donation_2", that will then be used in an additional Checkout Flow that I must manually create?

Maybe my disconnect is that I am expecting the donation route to use one flow, and normal ecommerce to use another flow. I don't want ecommerce customers to be able to "also donate" in the same checkout, and likewise I do not want donation customers to be able to "also order a product" in the same checkout.

With that personal requirement in mind, is that possible with this module?

It's not possible with the provided checkout panes.

The client that this module was developed to support did not have any commerce beyond donations. After this code was released as a contributed module, donations along side the purchase of actual goods was requested by several users and I built a second checkout flow plugin to support that. However, all the plugins in this module are built to support the dedicated donation OrderItem. OrderItems are always paired with an Order in Commerce which is paired with a Checkout flow. So to support two flows, the checkout panes and the Donation order controller would all need to be configurable as to which OrderItem was expected in each flow. That's not the current state of the code.

OK thank you for your patience, greatly appreciated!

Absolutely! Happy to help.