chore: simpliflies handling of k8s not-found errors

[bartoszmajsak]

Instead of

if apierrs.IsNotFound(err) {
	return nil
}
return err

we can use

return client.IgnoreNotFound(err)

[openshift-ci]

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[zdtsw]

we have a bunch of in the upgrade.go,
intended to keep them?

also some are actually done as
if k8serrors.IsNotFound(err) { ... }
should be converted too?

[bartoszmajsak]

we have a bunch of in the upgrade.go, intended to keep them?

also some are actually done as if k8serrors.IsNotFound(err) { ... } should be converted too?

I looked at those too, but they're are a bit different

Multierrors

opendatahub-operator/pkg/upgrade/upgrade.go

Lines 501 to 505 in c04130f

	if apierrs.IsNotFound(err) {
	fmt.Printf("Could not find %s in namespace %s\n", item.GetName(), namespace)
	} else {
	multiErr = multierror.Append(multiErr, err)
	}

I can change this as part of this PR. Append(err error, errs ...error) ignores any nils passed as errs, so that's easy. But we still might want to log it? Or should I skip log message for this? What is the value of this information @zdtsw?

Wrapping errors

opendatahub-operator/pkg/upgrade/upgrade.go

Lines 308 to 313 in c04130f

	if apierrs.IsNotFound(err) {
	// If no Crd found, return, since its a new Installation
	// return empty list
	return nil
	}
	return fmt.Errorf("error retrieving kfdef CRD : %w", err)

This needs some wrapper func as fmt.Errorf does not seem to ignore nil errors - it's simply constructing the message with nil struct used for %w substitution.

We are using github.com/pkg/errors in a few places and errors.Wrap could handle that, but I think we should first discuss how to uniformly handle errors across the entire code base.