websocket-client: Release 1.0.0 caused an AttributeError: 'NoneType' object has no attribute 'settimeout' on websocketapp.close()

Hi,

With the 1.0.0 release, a major update in WebSocket.close() function in _core.py was done and it causes an AttributeError when we try to close WebSocketApp.

This issue is a side effect of an update in websocket-client/_core.py file

Initially, the code of WebSocket.close() function was:

    def close(self, status=STATUS_NORMAL, reason=six.b(""), timeout=3):
            ....
            try:
                ....
                self.sock.settimeout(sock_timeout)
                self.sock.shutdown(socket.SHUT_RDWR)
            except:
                pass

Now, exceptions are no more catched … except for Mac OS (!?!) :

    def close(self, status=STATUS_NORMAL, reason=bytes('', encoding='utf-8'), timeout=3):
            ....
            try:
                ....
                self.sock.settimeout(sock_timeout)
                self.sock.shutdown(socket.SHUT_RDWR)
           except OSError:  # This happens often on Mac
                pass
            except:
                raise

I found one reason that could cause self.sock set to None : when frame is decoded (line 479: frame = self.recv_frame()), if there is any error during decoding, the web socket is closed and set to None:

    def _recv(self, bufsize):
        try:
            return recv(self.sock, bufsize)
        except WebSocketConnectionClosedException:
            if self.sock:
                self.sock.close()
            self.sock = None
            self.connected = False
            raise

I suppose our issue isn’t new but was hidden by the try / except pass until 1.0.0 release.

Could you test self.sock before trying to set timeout and call shutdown() ?