don't show errors as public images won't have any creds

extension/credentialshelper/credentialshelper.go

@@ -95,6 +95,6 @@ func GetCredentials(image *types.TrackedImage) (creds *types.Credentials) {
 	}
 	log.WithFields(log.Fields{
 		"tracked_image": image,
-	}).Error("extension.credentialshelper: credentials helper not found")
+	}).Debug("extension.credentialshelper: credentials helper not found")
 	return creds
 }