Skip unsupported icon formats in PackageWrapper.LoadIconAsync

The icon cache (IconCacheEngine.MimeToExtension) writes files in formats
Avalonia's Skia Bitmap cannot decode: SVG, AVIF, ICO, TIFF. Passing such
a file to `new Bitmap(uri.LocalPath)` throws
ArgumentException("Unable to load bitmap from provided data"). The
exception is caught and the failure is cached, but Rider's debugger
surfaces every first-chance throw, so users see a flood of stack traces
whenever the package list brings new rows with non-raster icons into
view (e.g. after typing in the search bar).

Whitelist PNG/JPEG/GIF/BMP/WebP — the formats Skia can actually decode —
and short-circuit unsupported extensions to a cached-null result. The
package falls back to its manager source icon, same as before.

Author: GabrielDuf

src/UniGetUI.Avalonia/Models/PackageCollections.cs

@@ -201,6 +201,13 @@ private async Task LoadIconAsync()
 
                 if (uri.IsFile)
                 {
+                    if (!IsSkiaDecodableExtension(uri.LocalPath))
+                    {
+                        // Avalonia's Bitmap (Skia) can't decode SVG/AVIF/ICO/TIFF — the
+                        // icon cache may produce those. Reject upfront so we don't throw.
+                        _iconCache[hash] = null;
+                        return;
+                    }
                     bitmap = await Task.Run(() => new Bitmap(uri.LocalPath)).ConfigureAwait(false);
                 }
                 else if (uri.Scheme is "http" or "https")
@@ -223,6 +230,17 @@ private async Task LoadIconAsync()
         catch { _iconCache[hash] = null; }
     }
 
+    private static bool IsSkiaDecodableExtension(string path)
+    {
+        string ext = Path.GetExtension(path);
+        return ext.Equals(".png", StringComparison.OrdinalIgnoreCase)
+            || ext.Equals(".jpg", StringComparison.OrdinalIgnoreCase)
+            || ext.Equals(".jpeg", StringComparison.OrdinalIgnoreCase)
+            || ext.Equals(".gif", StringComparison.OrdinalIgnoreCase)
+            || ext.Equals(".bmp", StringComparison.OrdinalIgnoreCase)
+            || ext.Equals(".webp", StringComparison.OrdinalIgnoreCase);
+    }
+
     private void Package_PropertyChanged(object? sender, PropertyChangedEventArgs e)
     {
         if (e.PropertyName == nameof(Package.Tag))