Let's not send "incomplete donation" email if it's incomplete due to backend errors

[cellio]

If a logged-in user starts a donation but doesn't complete it, we (once) send email about it. The email is well-written and not naggy, but it does assume that the incomplete transaction was the user's doing. ​I think we intended it for the case where the user might have meant to complete the transaction and maybe even thought it was complete (missed a final click).

We recently had some problems with Stripe, so users trying to make donations got error messages. Then they got email asking about the incomplete transaction. Beyond Stripe errors, we could theoretically have some other server error, like the API call failing or timing out or something. Can we not send the email if the attempted donation produced an error?

I really hope this is a rare occurrence, but it's also something that can aggravate the affected people. Can we add this check to our send-email logic?