fix(client): skipnode utilization for PreCopy

Co-authored-by: George Jenkins <gvjenkins@gmail.com>
Signed-off-by: Brandt Keller <43887158+brandtkeller@users.noreply.github.com>
(cherry picked from commit a18a52e898)

pkg/registry/client.go

@@ -490,7 +490,7 @@ func (c *Client) Pull(ref string, options ...PullOption) (*PullResult, error) {
 			PreCopy: func(_ context.Context, desc ocispec.Descriptor) error {
 				mediaType := desc.MediaType
 				if i := sort.SearchStrings(allowedMediaTypes, mediaType); i >= len(allowedMediaTypes) || allowedMediaTypes[i] != mediaType {
-					return nil
+					return oras.SkipNode
 				}
 
 				mu.Lock()