Gocardless correction (#15554)

diff --git a/erpnext/templates/pages/integrations/gocardless_checkout.py b/erpnext/templates/pages/integrations/gocardless_checkout.py
index 2ba7001..8d77245 100644
--- a/erpnext/templates/pages/integrations/gocardless_checkout.py
+++ b/erpnext/templates/pages/integrations/gocardless_checkout.py
@@ -46,8 +46,10 @@
 		prefilled_customer = {
 			"company_name": payer.name,
 			"given_name": primary_contact.first_name,
-			"family_name": primary_contact.last_name,
 		}
+		if primary_contact.last_name is not None:
+			prefilled_customer.update({"family_name": primary_contact.last_name})
+
 		if primary_contact.email_id is not None:
 			prefilled_customer.update({"email": primary_contact.email_id})
 		else: