GDT editor: unable to specify Literal value or Template key for domain objects as Condition BRL fragment

Guided Decision Table: When adding a Condition BRL fragment it is not possible to enter a template key or value for an attribute on a domain object.

In the attached screen shot, when clicking pencil icon, nothing appear.
This is confirmed by both FireFox anc Chrome.
At that time, the following error is shown in browser's console.

[Chrome]
12:44:40 SEVERE [LogConfiguration] Exception caught: (TypeError) : Cannot read property 'indexOf' of null

[FireFox]
00:10:46 SEVERE [LogConfiguration] Exception caught: (TypeError) : b.indexOf is null