pizza-effects.ts

import { Store, Action, ofType } from '@ngrx/store';
import { catchError } from 'rxjs/operators';
import { of } from 'rxjs/observable/of';
import { switchMap, map } from 'rxjs/operators';

export class EffectError implements Action {
    readonly type = '[Error] Effect Error';
}

@Injectable()
export class PizzaEffects {

    constructor(
        private store: Store<any>,
        private update$: Actions,
        private pizzaService: PizzaService
    ) {}

    @Effect()
    loadPizza$ = this.update$.pipe(
        ofType('LOAD_PIZZA'),
        map((action: LoadPizza) => action.payload),
        switchMap((pizzaId: string) => 
            this.pizzaService.get(pizzaId).pipe(
                map((pizza: Pizza) => new LoadPizzaSuccess(pizza)),
                catchError(() => of(new EffectError()))
            ))
    );
}

import { Injectable } from '@angular/core';
import { Effect, Actions, ofType } from '@ngrx/effects';
import { of } from 'rxjs';
import { catchError, switchMap } from 'rxjs/operators';

If this is for Angular6/rxjs6 the these are the missing/updated imports which is causing confusion in your article.