Hello,
Try to do the same order but this time, choose another language (English), if it correct the problem
it would mean it's related to your mails translation files.
I had the very same error with the french translation:
Under /mails/en (English), you should have
order_conf_product_list.tpl
order_conf_product_list.txt
Under /mails/fr/ (French)
those two files were missing, copy them there