Only pass billing address details if they are present.

app/controllers/spree/checkout_controller_decorator.rb

@@ -390,18 +390,19 @@ module Spree
 
       # suggest current user's email or any email stored in the order
       opts[:email] = spree_current_user ? spree_current_user.email : order.email
-      opts[:address_override] = 1
+      if order.bill_address.present?
-      opts[:address] = {
+        opts[:address_override] = 1
-        :name => order.bill_address.full_name,
+        opts[:address] = {
-        :zip => order.bill_address.zipcode,
+          :name => order.bill_address.full_name,
-        :address1 => order.bill_address.address1,
+          :zip => order.bill_address.zipcode,
-        :address2 => order.bill_address.address2,
+          :address1 => order.bill_address.address1,
-        :city => order.bill_address.city,
+          :address2 => order.bill_address.address2,
-        :phone => order.bill_address.phone,
+          :city => order.bill_address.city,
-        :state => order.bill_address.state_text,
+          :phone => order.bill_address.phone,
-        :country => order.bill_address.country.iso
+          :state => order.bill_address.state_text,
-      }
+          :country => order.bill_address.country.iso
-
+        }
+      end
       opts
     end