non-nullable.ts

import { filter, map, Observable, OperatorFunction } from 'rxjs';

export function nonNullable<T>(): OperatorFunction<T, NonNullable<T>> {
  return function (source$: Observable<T>): Observable<NonNullable<T>> {
    return source$.pipe(
      filter(value => value != null),
      map(value => value!)
    );
  };
}