Grammar without references generates invalid ast.js.

[dslmeinte]

Langium version: 0.1.0
Package name: ?

Steps To Reproduce

1. Make a grammar without references (...=[Person|ID]).
2. Run langium:generate.

The current behavior

src/generated/ast.ts has a syntax error at export type <language name>AstReference = ;

The expected behavior

I guess never would work as RHS value if there are no references.

[msujew]

Thanks for your issue @dslmeinte. I think never is an appropriate type as well, especially since the generated getReferenceType method will always throw on any input.