New Angular Projects are created with the tsConfig flag isolatedModules set to true.
In order to support this flag, the library should export interfaces and type aliases in barrel files with the type only modifier like

export type { User } from './models/user';

afaik it only concerns the the non-enums of the models and the StrictHttpResponse in the index barrel file and models barrel file.

I will open a PR to do as described - would be nice if this small improvement could be merged :)