Show warning if no report title

App.axaml

@@ -97,6 +97,9 @@
         <DataTemplate DataType="{x:Type viewModels:AboutViewModel}">
             <views:AboutView/>
         </DataTemplate>
+        <DataTemplate DataType="{x:Type viewModels:WarningViewModel}">
+            <views:WarningView/>
+        </DataTemplate>
     </Application.DataTemplates>
     <Application.Resources>
         <ResourceDictionary>

ViewModels/MainViewModel.cs

@@ -205,6 +205,12 @@ class MainViewModel : BaseViewModel, IFontResolver
     }
 
     public async void BuildPDF()
+    {
+        if (string.IsNullOrWhiteSpace(ReportTitle))
+        {
+            await DialogHost.Show(new WarningViewModel("You must provide a report title!"));
+        }
+        else
         {
             try
             {
@@ -227,6 +233,7 @@ class MainViewModel : BaseViewModel, IFontResolver
                 }
             }
         }
+    }
 
     public byte[]? GetFont(string faceName)
     {

Views/WarningView.axaml

@@ -10,16 +10,20 @@
              x:DataType="vm:WarningViewModel">
     <StackPanel Orientation="Vertical"
                 Spacing="4">
+        <TextBlock TextAlignment="Center"
+                   FontWeight="Bold"
+                   FontSize="18"
+                   Text="Error!"/>
         <TextBlock TextAlignment="Center"
                    FontWeight="Bold"
                    TextWrapping="Wrap"
-                   FontSize="16"
+                   FontSize="14"
                    MaxWidth="350"
                    Text="{Binding Error}"/>
         <Button Command="{Binding Close}"
                 Classes="accent"
                 Content="Close"
                 HorizontalAlignment="Right"
-                Margin="0,0,4,4"/>
+                Margin="0,4,4,4"/>
     </StackPanel>
 </UserControl>