fix attribute error

lbry/wallet/network.py

@@ -284,12 +284,13 @@ class Network:
 
     async def subscribe_address(self, address, *addresses):
         addresses = list((address, ) + addresses)
+        server_addr_and_port = self.client.server_address_and_port  # on disconnect client will be None
         try:
             return await self.rpc('blockchain.address.subscribe', addresses, True)
         except asyncio.TimeoutError:
             log.warning(
                 "timed out subscribing to addresses from %s:%i",
-                *self.client.server_address_and_port
+                *server_addr_and_port
             )
             # abort and cancel, we can't lose a subscription, it will happen again on reconnect
             if self.client: