Please replace in example-app: books$: Observable<Book[]>; with books$: Observable<(Book|undefined)[]>;

[mare25]

Minimal reproduction of the bug/regression with instructions:

Expected behavior:

Versions of NgRx, Angular, Node, affected browser(s) and operating system(s):

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)
[ ] No

[alex-okrushko]

I think this is related to the change in the Dictionary.
I'll take a look.