Fix kubectl panic when handling invalid error.

Kubernetes-commit: 12d944b860e4872085fa1155590c7fcef58e6bb8

pkg/cmd/util/helpers.go

@@ -131,9 +131,13 @@ func checkErr(err error, handleErr func(string, int)) {
 		handleErr("", DefaultErrorExitCode)
 	case kerrors.IsInvalid(err):
 		details := err.(*kerrors.StatusError).Status().Details
-		s := fmt.Sprintf("The %s %q is invalid", details.Kind, details.Name)
-		if len(details.Kind) == 0 && len(details.Name) == 0 {
-			s = "The request is invalid"
+		s := "The request is invalid"
+		if details == nil {
+			handleErr(s, DefaultErrorExitCode)
+			return
+		}
+		if len(details.Kind) != 0 || len(details.Name) != 0 {
+			s = fmt.Sprintf("The %s %q is invalid", details.Kind, details.Name)
 		}
 		if len(details.Causes) > 0 {
 			errs := statusCausesToAggrError(details.Causes)

pkg/cmd/util/helpers_test.go

@@ -19,6 +19,7 @@ package util
 import (
 	"fmt"
 	"io/ioutil"
+	"net/http"
 	"os"
 	"strings"
 	"syscall"
@@ -226,6 +227,16 @@ func TestCheckInvalidErr(t *testing.T) {
 			"The Invalid4 \"invalidation\" is invalid: field4: Invalid value: \"multi4\": details\n",
 			DefaultErrorExitCode,
 		},
+		{
+			&errors.StatusError{metav1.Status{
+				Status: metav1.StatusFailure,
+				Code:   http.StatusUnprocessableEntity,
+				Reason: metav1.StatusReasonInvalid,
+				// Details is nil.
+			}},
+			"The request is invalid",
+			DefaultErrorExitCode,
+		},
 	})
 }