After OCPBUGS-13726, Hypershift honors ImageConfig provided by the user in the HostedCluster.
Providing both allowedRegistries and blockedRegistries is forbidden https://github.com/openshift/api/blob/1e963d8dc4663f4f004f44fd58459381a771bdb5/config/v1/types_image.go#L126
If we do that in HyperShift, it will block any NodePool creation but no error is visible in the HostedCluster, so it is not easy to identify the error.
The error should instead be visible in the existing HC condition ValidHostedControlPlaneConfiguration

    4.15.6

    Always

    1. Create HC
    2. oc patch hc -n $HC_NS $HC_NAME -p '{"spec":{"configuration":{"image":{"registrySources":{"allowedRegistries":["docker.io"], "blockedRegistries":["test.io"]}}}}}' --type=merge
     3. New node pools not coming up and condition visible in the NP 
    

  - lastTransitionTime: "2024-04-11T12:49:32Z"
    message: 'Failed to generate payload: error getting ignition payload: failed to
      execute machine-config-controller: machine-config-controller process failed:
      exit status 255'
    observedGeneration: 1
    reason: InvalidConfig
    status: ""
    type: ValidGeneratedPayload

    HC condition successful

  - lastTransitionTime: "2024-04-11T08:59:01Z"
    message: Configuration passes validation
    observedGeneration: 4
    reason: AsExpected
    status: "True"
    type: ValidHostedControlPlaneConfiguration

    Above HC condition to be failed