After prepayment fails lnd keeps trying to pay the swap, delaying failure notification.

A successful loop out involves two off chain payments: the prepay and the swap.

If the prepay fails early, the swap is bound to fail, but loop never communicates to lnd that it should stop trying to make this payment.

Once one of the offchain payment fails, we should ask lnd to "stop trying" to fulfill the other payment. We can't rely on lnd's timeout, since loop sets this to 60 minutes (this makes sense, since the swap payments might take a while to find a route).

Edit:

I'm on version v0.23.0-beta

No file or test is named. Start by tracing loop out's prepay and swap payment handling, then inspect how failed payments are reported and whether the other payment can be stopped through the lnd integration. Done means that failure of either off-chain payment stops the other promptly and failure notification is no longer delayed by the 60-minute timeout.

Written by the indexing model from the issue text.