public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            Init();

        }

        private void Init()
        {
            try
            {
                Console.WriteLine("Anfang");
                TextBlock tb = new TextBlock();
                tb.Text = "Text";
                grid.Children.Add(tb);
                Console.WriteLine("Fertig");
            }
            catch
            {
                throw;
            }
        }
    }

catch (Exception ex)
            {
                Console.Writeline(ex.Message)
            }

//App.xaml.cs
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Threading;

namespace WpfApplication4
{
    /// <summary>
    /// Interaktionslogik für "App.xaml"
    /// </summary>
    public partial class App : Application
    {
        public App() : base()
        {
            SetupUnhandledExceptionHandling();
        }

        private void SetupUnhandledExceptionHandling()
        {
            // Catch exceptions from all threads in the AppDomain.
            AppDomain.CurrentDomain.UnhandledException += (sender, args) =>
                ShowUnhandledException(args.ExceptionObject as Exception, "AppDomain.CurrentDomain.UnhandledException", false);

            // Catch exceptions from each AppDomain that uses a task scheduler for async operations.
            TaskScheduler.UnobservedTaskException += (sender, args) =>
                ShowUnhandledException(args.Exception, "TaskScheduler.UnobservedTaskException", false);

            // Catch exceptions from a single specific UI dispatcher thread.
            Dispatcher.UnhandledException += (sender, args) =>
            {
                // If we are debugging, let Visual Studio handle the exception and take us to the code that threw it.
                if (!Debugger.IsAttached)
                {
                    args.Handled = true;
                    ShowUnhandledException(args.Exception, "Dispatcher.UnhandledException", true);
                }
            };

            // Catch exceptions from the main UI dispatcher thread.
            // Typically we only need to catch this OR the Dispatcher.UnhandledException.
            // Handling both can result in the exception getting handled twice.
            //Application.Current.DispatcherUnhandledException += (sender, args) =>
            //{
            //	// If we are debugging, let Visual Studio handle the exception and take us to the code that threw it.
            //	if (!Debugger.IsAttached)
            //	{
            //		args.Handled = true;
            //		ShowUnhandledException(args.Exception, "Application.Current.DispatcherUnhandledException", true);
            //	}
            //};
        }

        void ShowUnhandledException(Exception e, string unhandledExceptionType, bool promptUserForShutdown)
        {
            //var messageBoxTitle = $"Unexpected Error Occurred: {unhandledExceptionType}";
            var messageBoxMessage = $"The following exception occurred:\n\n{e}";
            //var messageBoxButtons = MessageBoxButton.OK;

            if (promptUserForShutdown)
            {
                messageBoxMessage += "\n\nNormally the app would die now. Should we let it die?";
                //messageBoxButtons = MessageBoxButton.YesNo;
            }

            // Let the user decide if the app should die or not (if applicable).
            Console.WriteLine(messageBoxMessage);
            //if (MessageBox.Show(messageBoxMessage, messageBoxTitle, messageBoxButtons) == MessageBoxResult.Yes)
            //{
            //    Application.Current.Shutdown();
            //}
        }
    }
}

 //MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Text;
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 WpfApplication4
{
    /// <summary>
    /// Interaktionslogik für MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            Init();

        }

        private void Init()
        {
            try
            {
                Console.WriteLine("Anfang");
                TextBlock tb = new TextBlock();
                tb.Text = "Text";
                grid.Children.Add(tb);
                Console.WriteLine("Fertig");
            }
            catch(Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}