Sanitation [skip ci]

Former-commit-id: 75afdcee89a077e71c541a528bef5dc73ba8841b
Former-commit-id: cbc78b6631dedb8c625b755d9cb7d7eb6be62d95
Former-commit-id: 442f01311ac24030e7a3894bfe0a431ea5fde2ee

src/ImageProcessorCore/Samplers/ImageSamplerExtensions.cs

@@ -40,6 +40,9 @@ namespace ImageProcessorCore.Samplers
         /// <returns>The <see cref="Image"/></returns>
         public static Image Crop(this Image source, int width, int height, Rectangle sourceRectangle, ProgressEventHandler progressHandler = null)
         {
+            Guard.MustBeGreaterThan(width, 0, nameof(width));
+            Guard.MustBeGreaterThan(height, 0, nameof(height));
+            
             if (sourceRectangle.Width < width || sourceRectangle.Height < height)
             {
                 // If the source rectangle is smaller than the target perform a
@@ -183,6 +186,9 @@ namespace ImageProcessorCore.Samplers
                 height = source.Height * width / source.Width;
             }
 
+            Guard.MustBeGreaterThan(width, 0, nameof(width));
+            Guard.MustBeGreaterThan(height, 0, nameof(height));
+
             Resize processor = new Resize(sampler) { Compand = compand };
             processor.OnProgress += progressHandler;