Forgetting to inform the customer of the different sizes of the item for sale
Q: I sell products online through Etsy. I sold a desk mat through Bay‘ al-Salam. The mat has three sizes, but I accidentally forgot to add the size variations to the listing. The displayed price was for the smallest size, and I delivered that smallest size to the customer. I did not intend to deceive the customer; it was an honest mistake. The customer accepted the item without requesting a refund.
Is the Salam transaction valid, and is my earning halal? Does the hadith that Allah has pardoned mistakes and forgetfulness apply in this situation?