[DMN Designer] It is not possible to add constraints to nested data types

When creating a Custom Data Type it is not possible to add contraints to nested data types.

By clicking on the icon add constraints of a nested type, a popup window is presented. However, it is not possible to add any constraint types.

Documentation 3.2 step 7

Steps to reproduce:

1 - Click on tab Data Types

2 - Create a new data type

3 - Add a nested String data type to it

4 - Click on edit icon then on add constraints icon  

5 - Select  Enumeration as constraint type

The following errors are being presented in the VSCode console, and it is not possible to definine enumenration items: