htlcswitch: update getChanID to be aware of FundingLocked

In this commit, we update getChanID to be aware of the FundingLocked
message as it will be retransmitted upon reconnect if both nodes think
that they’re at the very first commitment state.

htlcswitch/test_utils.go

@@ -358,8 +358,10 @@ func getChanID(msg lnwire.Message) (lnwire.ChannelID, error) {
 		chanID = msg.ChanID
 	case *lnwire.ChannelReestablish:
 		chanID = msg.ChanID
+	case *lnwire.FundingLocked:
+		chanID = msg.ChanID
 	default:
-		return chanID, errors.New("unknown type")
+		return chanID, fmt.Errorf("unknown type: %T", msg)
 	}
 
 	return chanID, nil