Add WarningView

ViewModels/WarningViewModel.cs

@@ -0,0 +1,25 @@
+#nullable enable
+
+using DialogHostAvalonia;
+
+namespace ReceiptPDFBuilder.ViewModels;
+
+class WarningViewModel
+{
+    private string _error;
+
+    public WarningViewModel(string error)
+    {
+        _error = error;
+    }
+
+    public string Error
+    {
+        get => _error;
+    }
+
+    public void Close()
+    {
+        DialogHost.Close("DialogHost", null);
+    }
+}

Views/WarningView.axaml

@@ -0,0 +1,25 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             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"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="ReceiptPDFBuilder.Views.WarningView"
+             xmlns:models="clr-namespace:ReceiptPDFBuilder.Models"
+             xmlns:vm="clr-namespace:ReceiptPDFBuilder.ViewModels"
+             xmlns:dialogHost="clr-namespace:DialogHostAvalonia;assembly=DialogHost.Avalonia"
+             x:DataType="vm:WarningViewModel">
+    <StackPanel Orientation="Vertical"
+                Spacing="4">
+        <TextBlock TextAlignment="Center"
+                   FontWeight="Bold"
+                   TextWrapping="Wrap"
+                   FontSize="16"
+                   MaxWidth="350"
+                   Text="{Binding Error}"/>
+        <Button Command="{Binding Close}"
+                Classes="accent"
+                Content="Close"
+                HorizontalAlignment="Right"
+                Margin="0,0,4,4"/>
+    </StackPanel>
+</UserControl>

Views/WarningView.axaml.cs

@@ -0,0 +1,15 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace ReceiptPDFBuilder.Views
+{
+    public partial class WarningView : UserControl
+    {
+        public WarningView()
+        {
+            this.InitializeComponent();
+        }
+    }
+}