Creem checkout creation fails 400 'customer.email is invalid' when user has no bound email

Problem

Creating a Creem hosted checkout from a backend that always sends customer: {email: ""} fails for accounts without an email.

Error (redacted / normalized)

{"statusCode":400,"message":"customer.The customer email is invalid"}

Applies when

Creem API v1 /checkouts, backend forwarding user profile

Root cause

Creem validates the customer object if present; an empty string is an invalid email. Omitting customer entirely lets Creem collect the email on the hosted page.

Fix

1. Only include customer when the email is non-empty after trim.
2. Otherwise omit the field; keep request_id/metadata so the webhook can map the order.

How to verify

POST /v1/checkouts returns 200 with a checkout_url for a user with no email.

What did not work

Sending customer: null; sending a placeholder email.

Risks

None.