htlcswitch: interceptor expiry check

htlcswitch/mock.go

@@ -185,7 +185,7 @@ func initSwitchWithDB(startingHeight uint32, db *channeldb.DB) (*Switch, error)
 			events: make(map[time.Time]channeldb.ForwardingEvent),
 		},
 		FetchLastChannelUpdate: func(lnwire.ShortChannelID) (*lnwire.ChannelUpdate, error) {
-			return nil, nil
+			return &lnwire.ChannelUpdate{}, nil
 		},
 		Notifier: &mock.ChainNotifier{
 			SpendChan: make(chan *chainntnfs.SpendDetail),