fix(client): return nil on non-allowed media types

Signed-off-by: Brandt Keller <brandt.keller@defenseunicorns.com>
(cherry picked from commit c225c124ac)

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 errors.Errorf("media type %q is not allowed, found in descriptor with digest: %q", mediaType, desc.Digest)
+					return nil
 				}
 
 				mu.Lock()