## Minimal reproduction of the bug with instructions: This bug was replicated locally and on stackblitz [StackBlitz Link](https://stackblitz.com/edit/angular-extensions-model?file=src%2Fapp%2Ftodo%2Ftodo.service.ts ) 1) Open stackblitz from demo app. 2) When "addTodo(name: string) 3) Check type returned form this.model.get(); type = Object[] ## Expected behavior: Type should be Todo[] ## Other information: ## I would be willing to submit a PR to fix this issue: [ ] Yes (Assistance is provided if you need help submitting a pull request) [ x] No <!-- If you are willing to submit a PR but are a bit unsure, feel free to check out the [Contributors Guide](CONTRIBUTING.md) for useful tips and hints that help you get started. -->