Getting error for adding MediaElement in ItemTemplate for WPF

Question

I have an application that gets all videos from an API for a search query and shows them as a grid with image by default. The received data also contains the URL for the video so I want to play the video when I hover over the image. But when I added the MediaElement for the video it gives me the error "NullReferenceException: Object reference not set to an instance of an object."

I have tried suppressing the warning using GetIsInDesignMode

 if (!System.ComponentModel.DesignerProperties.GetIsInDesignMode(this))
            {
                //Code that throws the exception
            }

But it doesn't help. The code for window.xaml is

<Window x:Class="ResponsiveGrid.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:ResponsiveGrid"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <ListBox x:Name="listbox1" ScrollViewer.HorizontalScrollBarVisibility="Disabled">
            <ListBox.ItemsPanel>
                <ItemsPanelTemplate>
                    <WrapPanel ItemHeight="250"
                               ItemWidth="250"
                               Orientation="Horizontal" />
                </ItemsPanelTemplate>
            </ListBox.ItemsPanel>
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid Width="250" Height="250">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition />
                            <ColumnDefinition />
                            <ColumnDefinition />
                        </Grid.ColumnDefinitions>
                        <Grid.RowDefinitions>
                            <RowDefinition  />
                            <RowDefinition />
                            <RowDefinition />
                        </Grid.RowDefinitions>
                        <Image  Source="" Grid.ColumnSpan="3" HorizontalAlignment="Left" Height="250" Grid.RowSpan="3" VerticalAlignment="Top" Width="250" Stretch="UniformToFill"/>
                        <MediaElement Source="" />

                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
        
    </Grid>
</Window>
using System;
using System.Collections.Generic;
using System.Linq;
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 ResponsiveGrid
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            if (!System.ComponentModel.DesignerProperties.GetIsInDesignMode(this))
            {
                //Code that throws the exception
            }
            listbox1.ItemsSource = Enumerable.Range(1, 100);
        }
    }
}