Avoid annoying exception on shutdown

lib/jsonrpc.py

@@ -79,16 +79,12 @@ class JSONRPC(asyncio.Protocol, LoggedClass):
         self.send_count = 0
         self.send_size = 0
         self.error_count = 0
+        self.peer_info = None
 
     def connection_made(self, transport):
         '''Handle an incoming client connection.'''
         self.transport = transport
-
-    def peer_info(self):
-        '''Return peer info.'''
-        if self.transport:
-            return self.transport.get_extra_info('peername')
-        return None
+        self.peer_info = transport.get_extra_info('peername')
 
     def connection_lost(self, exc):
         '''Handle client disconnection.'''

server/protocol.py

@@ -224,7 +224,7 @@ class Session(JSONRPC):
         self.manager.add_task(self, self.handle_json_request(request))
 
     def peername(self):
-        info = self.peer_info()
+        info = self.peer_info
         return 'unknown' if not info else '{}:{}'.format(info[0], info[1])
 
     def tx_hash_from_param(self, param):