[Bug] Default sample fails to export

[jcoliz]

1. Fresh install of 0.9.1
2. Immediately Export without making any changes.
3. Choose any output location
4. Press save

Result:
Output presentation is blank

Expected:
Properly exported

Logs:

2024-07-06 20:36:32.616 -07:00 [ERR] Export failed
System.ApplicationException: Unable to load image wine.png
 ---> System.InvalidOperationException: Sequence contains no elements
   at System.Linq.ThrowHelper.ThrowNoElementsException()
   at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)
   at LogoSlideMaker.Export.ImageCache.LoadImageAsync(String filename)
   at LogoSlideMaker.Export.ImageCache.LoadAsync(String path)
   --- End of inner exception stack trace ---
   at LogoSlideMaker.Export.ImageCache.LoadAsync(String path)
   at LogoSlideMaker.Export.ImageCache.LoadAsync(IEnumerable`1 paths)
   at LogoSlideMaker.Export.ExportPipeline.LoadAndMeasureAsync(String basePath)
   at LogoSlideMaker.WinUi.ViewModels.MainViewModel.ExportToAsync(String outPath)
   at LogoSlideMaker.WinUi.MainWindow.DoExport_Click(Object _, RoutedEventArgs __)