Prevent a crash in extensible items with default values.

Status Job ID Name Coverage
  External
passed cdash

passed ghostflow-branch-check-master

passed ghostflow-branch-check-release

failed smtk@master-kerbin-windows-shared-release+examples+remus

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+private+remus

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+python3+remus+vtk

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+remus

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+remus+vtk

running smtk@master-norkit-osx-shared-release+examples+matplotlib

756:26:43

failed smtk@master-praxis-windows-shared-release

failed smtk@master-talosiv-osx-shared-release+examples+matplotlib

failed smtk@master-tatooine-osx-shared-release+examples+matplotlib

failed smtk@master-tatooine-osx-shared-release+examples+matplotlib+private

failed smtk@release-moho-linux-shared-relwithdebinfo+remus

running smtk@release-praxis-windows-shared-release

756:25:13

passed cdash

passed cdash

passed cdash

failed smtk@master-kerbin-windows-shared-release+examples+remus

00:01:31

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+private+remus

00:03:23

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+python3+remus+vtk

00:00:07

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+remus

00:03:23

failed smtk@master-moho-linux-shared-relwithdebinfo+examples+remus+vtk

00:03:11

failed smtk@master-praxis-windows-shared-release

00:01:26

failed smtk@master-talosiv-osx-shared-release+examples+matplotlib

00:01:43

failed smtk@master-tatooine-osx-shared-release+examples+matplotlib

00:01:55

failed smtk@master-tatooine-osx-shared-release+examples+matplotlib+private

00:02:17

failed smtk@release-moho-linux-shared-relwithdebinfo+remus

00:00:03