Description of problem:

If one's quay.io credentials do not have correct permissions to pull the driver toolkit image, the SRO controller goes to a CrashLoopBackOff status.

How reproducible:
100%

Steps to Reproduce:
1. Deploy SRO from the 4.9 channel
2. Set the quay.io pull secret to one that does not have permissions to pull the DTK Images.
3. Apply the simple-kmod SR

Actual results:

2022-02-15T17:00:27.863Z        INFO    filter          CREATE IsSpecialResource (reflect)      {"Name": "simple-kmod", "Type": "*v1beta1.SpecialResource"}
2022-02-15T17:00:27.863Z        INFO    preamble        Controller Request      {"Name": "simple-kmod", "Namespace": ""}
2022-02-15T17:00:27.867Z        INFO    cache   Nodes cached    {"name": "cnfde9.ptp.lab.eng.bos.redhat.com"}
2022-02-15T17:00:27.867Z        INFO    cache   Node list:      {"length": 1}
2022-02-15T17:00:27.867Z        INFO    cache   Nodes   {"num": 1}
2022-02-15T17:00:27.872Z        INFO    upgrade         History {"entry": "quay.io/openshift-release-dev/ocp-release@sha256:5c55be02e32e688ec5a404858a08cf533ba15b50b6f0e028089635b47db5866e"}
2022-02-15T17:00:30.298Z        INFO    warning         OnError: Cannot extract manifest: GET https://quay.io/v2/openshift-release-dev/ocp-v4.0-art-dev/manifests/sha256:65369b6ccff0f3dcdaa8685ce4d765b8eba0438a506dad5d4221770a6ac1960a: UNAUTHORIZED: access to the requested resource is not a
uthorized; map[]                                                                                                                                 
2022-02-15T17:00:30.298Z        INFO    exit    OnError: upgrade.DriverToolkitVersion[upgrade.go:170] Cannot extract last layer for DTK from: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:65369b6ccff0f3dcdaa8685ce4d765b8eba0438a506dad5d4221770a6ac1960a  


Expected results:
A valid BuildConfig

Additional info:
There is an typo where the LastLayer function returns a 'nil' error where it should have returned the err.  This causes the calling function to think there was no error and de-reference the nil result.

https://github.com/openshift-psap/special-resource-operator/blob/master/pkg/registry/registry.go#L103


Patch to fix:
diff --git a/pkg/registry/registry.go b/pkg/registry/registry.go
index d937e663..2acfe305 100644
--- a/pkg/registry/registry.go
+++ b/pkg/registry/registry.go
@@ -101,7 +101,7 @@ func (r *registry) LastLayer(entry string) (v1.Layer, error) {
        manifest, err := crane.Manifest(entry, options)
        if err != nil {
                warn.OnError(fmt.Errorf("cannot extract manifest: %v", err))
-               return nil, nil
+               return nil, err
        }
 
        release := unstructured.Unstructured{}