`oc mirror` returns `401 Unauthorized` when mirroring images that do not exist

Issue

• When executing the oc mirror command with an image that does not exist in the mirror registry specified in the additionalImages of ImageSetConfiguration, the output is 401 Unauthorized.
• This implies insufficient authentication credentials, yet the error is displayed even when the credentials are correctly configured.
• This mismatch between the error message and the actual cause hinders users from identifying the root of the issue effectively.