[UI] [Error] File not found when loading last file

[jcoliz]

Given: Loaded an existing TOML
And: Closed app
And: Deleted that TOML
When: Launching the app
Then: Display an error message to user
And: Loads the embedded default slide

Currently: Just does loading spinner forever

Logs:

2024-07-09 13:10:13.525 -07:00 [ERR] LoadDefinitionAsync: Failed
System.IO.FileNotFoundException: Could not find file 'redacted.toml'.
File name: 'redacted.toml'
   at Microsoft.Win32.SafeHandles.SafeFileHandle.CreateFile(String fullPath, FileMode mode, FileAccess access, FileShare share, FileOptions options)
   at Microsoft.Win32.SafeHandles.SafeFileHandle.Open(String fullPath, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, Nullable`1 unixCreateMode)
   at System.IO.Strategies.OSFileStreamStrategy..ctor(String path, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, Nullable`1 unixCreateMode)
   at System.IO.Strategies.FileStreamHelpers.ChooseStrategyCore(String path, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, Nullable`1 unixCreateMode)
   at System.IO.File.OpenRead(String path)
   at LogoSlideMaker.WinUi.ViewModels.MainViewModel.LoadDefinitionAsync(String path)