Add an improved user error message for removed k8s apis

The error message returned from Kubernetes when APIs are
removed is not very informative. This PR adds additional
information to the user. It covers the current release manifest
APIs.

Partial #7219

Signed-off-by: Martin Hickey <martin.hickey@ie.ibm.com>

pkg/action/upgrade.go

@@ -233,6 +233,13 @@ func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[strin
 func (u *Upgrade) performUpgrade(originalRelease, upgradedRelease *release.Release) (*release.Release, error) {
 	current, err := u.cfg.KubeClient.Build(bytes.NewBufferString(originalRelease.Manifest), false)
 	if err != nil {
+		// Checking for removed Kubernetes API error so can provide a more informative error message to the user
+		// Ref: https://github.com/helm/helm/issues/7219
+		if strings.Contains(err.Error(), "unable to recognize \"\": no matches for kind") {
+			return upgradedRelease, errors.Wrap(err, "current release manifest contains removed kubernetes api(s) for this "+
+				"kubernetes version and it is therefore unable to build the kubernetes "+
+				"objects for performing the diff. error from kubernetes")
+		}
 		return upgradedRelease, errors.Wrap(err, "unable to build kubernetes objects from current release manifest")
 	}
 	target, err := u.cfg.KubeClient.Build(bytes.NewBufferString(upgradedRelease.Manifest), !u.DisableOpenAPIValidation)