WPF WebClient EAP async await

<Window x:Class="WpfApp40.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp40" WindowState="Maximized"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition Height="50"/>
        </Grid.RowDefinitions>
        <ScrollViewer Grid.Row="0">
            <TextBlock x:Name="_result"   HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
            FontSize="20"/>
        </ScrollViewer>
       
        <Button Grid.Row="1" x:Name="_loadBtn" Click="_loadBtn_Click" Content="Load Content" FontSize="20"
                HorizontalAlignment="Left" />
    </Grid>
</Window>




using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp40
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        string url = "https://learn.microsoft.com/en-us/";
        public MainWindow()
        {
            InitializeComponent();
        }

        private void _loadBtn_Click(object sender, RoutedEventArgs e)
        {
            var client = new WebClient();
            
            _result.Text = "Please wait...";
            client.DownloadStringCompleted += (s, args) =>
            {
                if(args.Error!=null)
                {
                    _result.Text = "Error:" + args.Error.Message;
                }
                else
                {
                    _result.Text = args.Result;
                }
            };
            client.DownloadStringAsync(new Uri(url));
        }
    }
}

//WebClient DownloadStringTaskAsync, async await 
private async void _loadBtn_Click(object sender, RoutedEventArgs e)
{
    var client = new WebClient();
    _result.Text = "Please wait...";
    try
    {
        _result.Text = await client.DownloadStringTaskAsync(url);
    }
    catch (WebException ex)
    {
        _result.Text = "Error: " + ex.Message;     
    }
}