From dff1822c370f0ee19dc3945ba741a30939e123d6 Mon Sep 17 00:00:00 2001
From: ThomasV <thomasv@electrum.org>
Date: Sat, 8 Jun 2019 18:37:15 +0200
Subject: [PATCH] fix watchtower: sweep_tx must not be None

---
 electrum/lnsweep.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/electrum/lnsweep.py b/electrum/lnsweep.py
index 372b6dd04..27f9cdcf5 100644
--- a/electrum/lnsweep.py
+++ b/electrum/lnsweep.py
@@ -55,7 +55,8 @@ def create_sweeptxs_for_their_revoked_ctx(chan: 'Channel', ctx: Transaction, per
             witness_script=witness_script,
             privkey=other_revocation_privkey,
             is_revocation=True)
-        txs.append(sweep_tx)
+        if sweep_tx:
+            txs.append(sweep_tx)
     # HTLCs
     def create_sweeptx_for_htlc(htlc: 'UpdateAddHtlc', is_received_htlc: bool) -> Tuple[Optional[Transaction],
                                                                                       Optional[Transaction],