Added handling for empty extension parameters in ImageFormatManager.TryFindFormatByFileExtension

src/ImageSharp/Formats/ImageFormatManager.cs

@@ -101,11 +101,14 @@ public class ImageFormatManager
     /// </param>
     /// <returns><see langword="true"/> if a match is found; otherwise, <see langword="false"/></returns>
     public bool TryFindFormatByFileExtension(string extension, [NotNullWhen(true)] out IImageFormat? format)
+    {
+        if (!string.IsNullOrWhiteSpace(extension))
         {
             if (extension[0] == '.')
             {
                 extension = extension[1..];
             }
+        }
 
         format = this.imageFormats.FirstOrDefault(x =>
             x.FileExtensions.Contains(extension, StringComparer.OrdinalIgnoreCase));