Non blocking read triggers log message about objc-zmq HOT 6 CLOSED

#pragma mark Communication
- (NSData *) recv:(ZMQMessageReceiveFlags) flags {
    zmq_msg_t data;
    int err = zmq_msg_init(&data);
    if (err) {
        ZMQLogError(self, @"zmq_msg_init");
        return nil;
    }

    errno = 0;
    err = zmq_recv(self.socket, &data, flags);
    if (err) {
        if (flags == ZMQ_NOBLOCK && errno == EAGAIN) {
            zmq_msg_close(&data);
            return nil;
        } else {
            ZMQLogError(self, @"zmq_recv");
            err = zmq_msg_close(&data);
            if (err) {
                ZMQLogError(self, @"zmq_msg_close");
            }
        }
    }

    size_t length = zmq_msg_size(&data);
    NSData *msg = [NSData dataWithBytes:zmq_msg_data(&data) length:length];

    err = zmq_msg_close(&data);
    if (err) {
        ZMQLogError(self, @"zmq_msg_close");
        /* fall through */
    }
    return msg;
}

<ZMQSocket: 0x9155cc0 (ctx=0x9153da0, type=ZMQ_XREQ, endpoint=tcp://10.8.8.18:12345, closed=0)>: zmq_recv: Undefined error: 0