refactor(*): update error message

Signed-off-by: Pavel Eremeev <selslack@users.noreply.github.com>

pkg/kube/client.go

@@ -334,11 +334,14 @@ func (c *Client) Update(namespace string, originalReader, targetReader io.Reader
 
 		originalInfo := original.Get(info)
 
-		// Resource exists in the current cluster state, but not in the current helm configuration
-		// See: https://github.com/helm/helm/issues/1193 for more info
+		// The resource already exists in the cluster, but it wasn't defined in the previous release.
+		// In this case, we consider it to be a resource that was previously un-managed by the release and error out,
+		// asking for the user to intervene.
+		//
+		// See https://github.com/helm/helm/issues/1193 for more info.
 		if originalInfo == nil {
 			return fmt.Errorf(
-				"%s %q is not managed by Helm; delete the resource from the current cluster state to let Helm manage it",
+				"kind %s with the name %q already exists in the cluster and wasn't defined in the previous release. Before upgrading, please either delete the resource from the cluster or remove it from the chart",
 				info.Mapping.GroupVersionKind.Kind,
 				info.Name,
 			)

pkg/kube/client_test.go

@@ -253,7 +253,7 @@ func TestUpdateNonManagedResourceError(t *testing.T) {
 	}
 
 	if err := c.Update(v1.NamespaceDefault, objBody(&current), objBody(&target), false, false, 0, false); err != nil {
-		if err.Error() != "Pod \"starfish\" is not managed by Helm; delete the resource from the current cluster state to let Helm manage it" {
+		if err.Error() != "kind Pod with the name \"starfish\" already exists in the cluster and wasn't defined in the previous release. Before upgrading, please either delete the resource from the cluster or remove it from the chart" {
 			t.Fatal(err)
 		}
 	} else {