htlcswitch: restore the ability to properly handle debughtlc recv's

This commit fixes a regression introduce in the prior commit which
added full verification of the per-hop payloads to the ChannelLink
interface. When this was initially implemented, the added checks
weren’t guarded on the existence of debughtlc’s. As a result,
debughtlc’s would be rejected as they don’t match the expected invoice
value.

This commit fixes that issue by only checking the hop payload if debug
HTLC mode isn’t on.

htlcswitch/link.go

@@ -928,7 +928,9 @@ func (l *channelLink) processLockedInHtlcs(
 				// extended. Additionally, we'll ensure that
 				// our time-lock value has been computed
 				// correctly.
-				if fwdInfo.AmountToForward != invoice.Terms.Value {
+				if !l.cfg.DebugHTLC &&
+					fwdInfo.AmountToForward != invoice.Terms.Value {
+
 					log.Errorf("Onion payload of incoming "+
 						"htlc(%x) has incorrect value: "+
 						"expected %v, got %v", pd.RHash,
@@ -940,7 +942,9 @@ func (l *channelLink) processLockedInHtlcs(
 					needUpdate = true
 					continue
 				}
-				if fwdInfo.OutgoingCTLV != l.cfg.FwrdingPolicy.TimeLockDelta {
+				if !l.cfg.DebugHTLC &&
+					fwdInfo.OutgoingCTLV != l.cfg.FwrdingPolicy.TimeLockDelta {
+
 					log.Errorf("Onion payload of incoming "+
 						"htlc(%x) has incorrect time-lock: "+
 						"expected %v, got %v",

htlcswitch/switch.go

@@ -628,7 +628,7 @@ func (s *Switch) htlcForwarder() {
 			// Otherwise, we'll log this diff, then accumulate the
 			// new stats into the running total.
 			log.Infof("Sent %v satoshis received %v satoshi "+
-				" in the last 10 seconds (%v tx/sec)",
+				"in the last 10 seconds (%v tx/sec)",
 				diffSatSent, diffSatRecv, float64(diffNumUpdates)/10)
 
 			totalNumUpdates += diffNumUpdates