added dialogue window if the user makes an unexpected / wrong input.

Project.View/NewLogin/NewLogin.axaml.cs

@@ -39,7 +39,11 @@ public partial class NewLogin : Window
         }
         else
         {
-            throw new Exception("Master Login Creation Failed");
+            NewLoginUsernameBox.Text = string.Empty;
+            NewLoginPasswordBox.Text = string.Empty;
+            NewLoginEmailBox.Text = string.Empty;
+            var ShowPopup = new PopUp();
+            ShowPopup.ShowDialog(this);
         }
     }
     

Project.View/PopUp/PopUp.axaml

@@ -0,0 +1,22 @@
+<Window
+    Height="250"
+    Title="WARNING"
+    Width="500"
+    WindowStartupLocation="CenterOwner"
+    x:Class="Project.View.PopUp"
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+
+    <StackPanel Margin="20" Spacing="10">
+        <TextBlock HorizontalAlignment="Center" Text="One or more of your inputs are missing or wrong." />
+        <TextBlock HorizontalAlignment="Center" Text="All fields must be filled." />
+        <TextBlock HorizontalAlignment="Center" Text="Your username needs at least 4 characters." />
+        <TextBlock HorizontalAlignment="Center" Text="Your password needs at least 8 characters." />
+        <TextBlock HorizontalAlignment="Center" Text="Make sure your email is correct." />
+        <Button
+            Click="OkButton_Click"
+            Content="OK"
+            HorizontalAlignment="Center"
+            Width="80" />
+    </StackPanel>
+</Window>

Project.View/PopUp/PopUp.axaml.cs

@@ -0,0 +1,21 @@
+using System;
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Media;
+using Project.Controller;
+using Project.Model;
+using Project.Persistence;
+
+namespace Project.View;
+
+public partial class PopUp : Window
+{        public PopUp()
+    {
+        InitializeComponent();
+    }
+
+    private void OkButton_Click(object? sender, RoutedEventArgs e)
+    {
+        Close();
+    }
+}