Pasting/typing emojis causes crash

[PathogenDavid]

I realize Emoji aren't supported yet, but I'd expect a � rather than a crash.

Environment

Observed in Synfonia (which I is using the latest Avalonia CI builds.)

I was not able to reproduce this with XamlControlsGallery, but I did run into a different issue there, see #4755 Edit: After modifying XamlControlsGallery to use the latest CI build, it crashes too.

Windows 10 2004

Steps to reproduce

1. Use Win+. to insert an emoji or copy paste this one into the search bar: 😂
2. There is no step 2

Expected behavior

No crash and the replacement character (�) appears.

Actual behavior

An AccessViolationException occurs within libSkiaSharp.dll:

 	libSkiaSharp.dll!00007ffeb9e54900()	Unknown
 	libSkiaSharp.dll!00007ffeb9ca8b1f()	Unknown
 	libSkiaSharp.dll!00007ffeb9bdc023()	Unknown
 	[Managed to Native Transition]	
 	SkiaSharp.dll!SkiaSharp.SKFont.MeasureText(void* text, int length, SkiaSharp.SKTextEncoding encoding, SkiaSharp.SKRect* bounds, SkiaSharp.SKPaint paint)	Unknown
 	SkiaSharp.dll!SkiaSharp.SKFont.MeasureText(System.ReadOnlySpan<char> text, SkiaSharp.SKPaint paint)	Unknown
 	SkiaSharp.dll!SkiaSharp.SKFont.MeasureText(string text, SkiaSharp.SKPaint paint)	Unknown
 	SkiaSharp.dll!SkiaSharp.SKPaint.MeasureText(string text)	Unknown
 	Avalonia.Skia.dll!Avalonia.Skia.FormattedTextImpl.BuildRects()	Unknown
 	Avalonia.Skia.dll!Avalonia.Skia.FormattedTextImpl.GetRects()	Unknown
 	Avalonia.Skia.dll!Avalonia.Skia.FormattedTextImpl.HitTestTextPosition(int index)	Unknown
 	Avalonia.Visuals.dll!Avalonia.Media.FormattedText.HitTestTextPosition(int index)	Unknown
 	Avalonia.Controls.dll!Avalonia.Controls.Presenters.TextPresenter.CaretIndexChanged.AnonymousMethod__0()	Unknown
 	Avalonia.Base.dll!Avalonia.Threading.JobRunner.Job.Avalonia.Threading.JobRunner.IJob.Run()	Unknown
 	Avalonia.Base.dll!Avalonia.Threading.JobRunner.RunJobs(Avalonia.Threading.DispatcherPriority? priority)	Unknown
 	Avalonia.Win32.dll!Avalonia.Win32.Win32Platform.WndProc(System.IntPtr hWnd, uint msg, System.IntPtr wParam, System.IntPtr lParam)	Unknown
 	[Native to Managed Transition]	
 	user32.dll!00007fff347be858()	Unknown
 	user32.dll!00007fff347be299()	Unknown
 	[Managed to Native Transition]	
 	Avalonia.Win32.dll!Avalonia.Win32.Win32Platform.RunLoop(System.Threading.CancellationToken cancellationToken)	Unknown
 	Avalonia.Base.dll!Avalonia.Threading.Dispatcher.MainLoop(System.Threading.CancellationToken cancellationToken)	Unknown
 	Avalonia.Controls.dll!Avalonia.Controls.ApplicationLifetimes.ClassicDesktopStyleApplicationLifetime.Start(string[] args)	Unknown
 	Avalonia.Controls.dll!Avalonia.ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime<Avalonia.AppBuilder>(Avalonia.AppBuilder builder, string[] args, Avalonia.Controls.ShutdownMode shutdownMode)	Unknown
>	Synfonia.Gui.dll!Synfonia.Program.Main(string[] args) Line 13	C#

[Takoooooo]

Fixed in #4893.

[PathogenDavid]

Awesome, thanks a lot @Takoooooo and @Gillibald!