In my current project I can't use the can be child/parent/ancestor functions because their completion menus are empty.
If I select node, for example, type . and press Ctrl+Space there are no entries in the completion menu.
In the inspector I see this text:
[operation] AbstractOperation <no name> in project.constraints
The text is underlined red and there is the following error message:
Error: Abstract concept instance detected. Use one of sub-concepts instead. Concept: AbstractOperation; owner is jetbrains.mps.typesystem.checking.TypesEditorChecker@1cecfdb6
I've tried this for different concepts always with the same result. Also rebuilding or reopen MPS does not change the behvior. In another project I can use the arguments as expected. There are no errors or warnings in my language, so I've no clue what's the reason for this misbehavior.
It would be great if anybody has a hint for me!