fix(storage): handle dedupe disabled in GetAllDedupeReposCandidates()

Signed-off-by: Petu Eusebiu <peusebiu@cisco.com>

Author: eusebiu-constantin-petu-dbk

pkg/storage/imagestore/imagestore.go

@@ -1121,9 +1121,14 @@ func (is *ImageStore) GetAllDedupeReposCandidates(digest godigest.Digest) ([]str
 		return nil, err
 	}
 
+	if is.cache == nil {
+		return nil, nil	
+	}
+
 	is.RLock(&lockLatency)
 	defer is.RUnlock(&lockLatency)
 
+	
 	blobsPaths, err := is.cache.GetAllBlobs(digest)
 	if err != nil {
 		return nil, err