peer: within loadActiveChannels, skip channel if FundingLocked not processed

This commit fixes a bug to wrap up the recently merged PR to properly
handle duplicate FundingLocked retransmissions and also ensure that we
reliably re-send the FundingLocked message if we’re unable to the first
time around.

In this commit, we skip processing a channel that does not yet have a
set remote revocation as otherwise, if we attempt to trigger a state
update, then we’ll be attempting to manipulate a nil commitment point.
Therefore, we’ll rely on the fundingManager to properly send the
channel all relevant subsystems.

peer.go

@@ -292,6 +292,18 @@ func (p *peer) loadActiveChannels(chans []*channeldb.OpenChannel) error {
 		}
 
 		chanPoint := &dbChan.FundingOutpoint
+
+		// If the channel we read form disk has a nil next revocation
+		// key, then we'll skip loading this channel. We must do this
+		// as it doesn't yet have the needed items required to initiate
+		// a local state transition, or one triggered by forwarding an
+		// HTLC.
+		if lnChan.RemoteNextRevocation() == nil {
+			peerLog.Debugf("Skipping ChannelPoint(%v), lacking "+
+				"next commit point", chanPoint)
+			continue
+		}
+
 		chanID := lnwire.NewChanIDFromOutPoint(chanPoint)
 
 		p.activeChanMtx.Lock()