Good day!
I discovered a typo in the "Custom Values" documentation for the ComboBox. On the page, under the Remote Services section, for the source of app.component.ts, there is a section of code:
/*
Maps each custom text that the user types to the result of a function that performs http request to remove service.
For further details about `switchMap` operator check:
http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-switchMap
*/
public valueNormalizer = (text: Observable<
string
>): any => text.pipe(switchMap(this.service));
On the comment line it states "...performs http request to remove service." I imagine you wanted that to be "....remote service.".
Peace,
Keith Nicholson