undefined is not an object (data)

I'm trying to implement socket.io-client in react-native, but it gives me an error.

Undefined is not an object (data)

sock = () => {
    const socket = openSocket(baseUrl);
    socket.on('newOrder', orders => {
      orders.length > 0
        ? this.setState(prevState => ({data: [...prevState.data, orders]}))
        : this.setState({
            data: [],
          });
    });
  };