Server-side error during checkout flow due to null response from getEntityIdByHandle('cart.php')

[artifact-hugo]

Hi,

Issue Description:
I have cloned a repository and connected it to my BigCommerce store. However, I encountered a server-side error during the checkout flow. Upon investigating the logs, I discovered that the response from getEntityIdByHandle('cart.php') is null: { status: 200, body: { data: { site: { route: { node: null } } } } }.

It seems that there might be some additional setup required for the embedded checkout flow. I would appreciate any guidance or suggestions to resolve this issue.

Additional Information:
BigCommerce Store: http://kintoki-ukiyoe.com

Logs:
Please find below the relevant log entries:

[GET] /cart.php TypeError: Cannot read properties of null (reading 'entityId')
    at (lib/bigcommerce/index.ts:85:39)
    at (lib/bigcommerce/index.ts:568:19)
    at (app/[page]/page.tsx:16:15)
   
[GET] /cart.php  Error: An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error. {
  digest: '3838381471'
}