Update TaskParameter.cs

Author: daniel-luberda

source/FFImageLoading.Common/Work/TaskParameter.cs

@@ -272,7 +272,8 @@ public TaskParameter ErrorPlaceholder(string filepath, ImageSource source = Imag
         public TaskParameter DownSample(int width = 0, int height = 0, bool? allowUpscale = null)
         {
             DownSampleUseDipUnits = false;
-
+			width = Math.Max(0, width);
+			height = Math.Max(0, height);
 			DownSampleSize = Tuple.Create(width, width > 0 ? 0 : height);
             AllowUpscale = allowUpscale;
 
@@ -291,7 +292,9 @@ public TaskParameter DownSample(int width = 0, int height = 0, bool? allowUpscal
 		public TaskParameter DownSampleInDip(int width = 0, int height = 0, bool? allowUpscale = null)
         {
             DownSampleUseDipUnits = true;
-            DownSampleSize = Tuple.Create(width, width > 0 ? 0 : height);
+			width = Math.Max(0, width);
+			height = Math.Max(0, height);
+			DownSampleSize = Tuple.Create(width, width > 0 ? 0 : height);
             AllowUpscale = allowUpscale;
 
             return this;