Fix deletion of first item in the list widget

When using the nxu:inputList widget, the displayed value when removing the first item is not accurate (but the value saved is ok).
Steps to reproduce: on the layout demo, for the list widget (string array):

• add 3 values to the list (foo, bar, baz) and submit
• delete the first value and submit
  => bar and baz are displayed in view mode (so they have been saved correctly) but the edit mode shows foo and baz