do not create backups for channels that do not have static_remotekey

electrum/lnchannel.py

@@ -461,6 +461,9 @@ class ChannelBackup(AbstractChannel):
     def is_frozen_for_receiving(self) -> bool:
         return False
 
+    def is_static_remotekey_enabled(self) -> bool:
+        return True
+
 
 class Channel(AbstractChannel):
     # note: try to avoid naming ctns/ctxs/etc as "current" and "pending".

electrum/lnworker.py

@@ -1360,6 +1360,8 @@ class LNWallet(LNWorker):
 
     def create_channel_backup(self, channel_id):
         chan = self._channels[channel_id]
+        # do not backup old-style channels
+        assert chan.is_static_remotekey_enabled()
         peer_addresses = list(chan.get_peer_addresses())
         peer_addr = peer_addresses[0]
         return ChannelBackupStorage(