How can I set my view model in data context while I'm using configurataion management.app setting reader in my view model constructor ?

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XAML

WPF

MVVM

I set My modelView in data context like the code below :
but I get this one error parameter name path cannot be null in this line :

<local:ViewModel/>

I limit the problem in the Text file reader used in my public model view ,
Cause when I changed the configuration management.appsetting with a simple string path the error has disappear .

My question is , how can I set My view model In data context while I'm using app config/setting configurataion management in my view model constructor ?

Thank you for you help and attention.

What I have tried:

<pre><Window x:Class="BancProduction.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:BancProduction"
        Title="MainWindow" Height="432.4" Width="687.4">
      
    <Window.DataContext>
        <local:ViewModel/>
    </Window.DataContext>

This is my first partcode of my Viewmodel:

namespace BancProduction
{
    class ViewModel : INotifyPropertyChanged
    {

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;
    

        #endregion
  
        public void RaisePropertyChanged([CallerMemberName] string str = "")
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(str));
            }
        }

 public search SearchCritaire
        {
            get
            {
                return Search;
            }
            set
            {
                if (value != Search)
                {
                    Search = value;
                    RaisePropertyChanged();
                }
            }
        }
     
        private ObservableCollection<search> famille;
   
        public ObservableCollection<search> Famille { get { return famille; }
            set { if (value != famille)
                {
                 famille = value; RaisePropertyChanged(); }
            
            } }

             public ViewModel()
        {   
          //this is the line reader that makes the error   
         string[] lineOfContents = File.ReadAllLines(ConfigurationManager.AppSettings["FiletextPath"]);

            MyList= new ObservableCollection<search>();           
           foreach (var line in lineOfContents)
           {
       string myline = line ;
                SearchCritaire = new search() { banc = line};
               

                MyList.Add(SearchCritaire);

            }

          }

this is my app config :

<?xml version="1.0"?>
<configuration>
  <appSettings>
    <add key="FiletextPath" value="D:\\Application Data\\Famille.txt"/>
    </appSettings>
</configuration>

I'm using the the binding method with view model , so I'm not working with the code behind method :

namespace BancProduction
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
}

}