acknowledge that creation of a restmapper can fail and that we cannot have a default

pkg/kubectl/cmd/rollout/rollout_undo.go

@@ -19,7 +19,6 @@ package rollout
 import (
 	"io"
 
-	"k8s.io/apimachinery/pkg/api/meta"
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	"k8s.io/kubernetes/pkg/api/legacyscheme"
 	"k8s.io/kubernetes/pkg/kubectl"
@@ -41,7 +40,6 @@ type UndoOptions struct {
 	ToPrinter  func(string) (printers.ResourcePrinterFunc, error)
 
 	Rollbackers []kubectl.Rollbacker
-	Mapper      meta.RESTMapper
 	Infos       []*resource.Info
 	ToRevision  int64
 	DryRun      bool
@@ -107,7 +105,6 @@ func (o *UndoOptions) CompleteUndo(f cmdutil.Factory, cmd *cobra.Command, out io
 	}
 
 	o.ToRevision = cmdutil.GetFlagInt64(cmd, "to-revision")
-	o.Mapper = f.RESTMapper()
 	o.Out = out
 	o.DryRun = cmdutil.GetDryRunFlag(cmd)