LNbits improperly handles potential network and payment failures when using Eclair backend

LNbits is a Lightning wallet and accounts system. Paying invoices in Eclair that do not get settled within the internal timeout (about 30s) lead to a payment being considered failed, even though it may still be in flight. This vulnerability can lead to a total loss of funds for the node backend. This vulnerability is fixed in 0.12.6.