ngrx-step2.ts

// -- error.actions.ts --
export class LaunchErrorModal implements Action {
  readonly type = ErrorActions.LaunchErrorModal;
}

export class MarkErrorModalAsOpen implements Action {
  readonly type = ErrorActions.MarkErrorModalAsOpen;
}

export class CloseErrorModal implements Action {
  readonly type = ErrorActions.CloseErrorModal;
}

export class UnmarkErrorModalAsOpen implements Action {
  readonly type = ErrorActions.UnmarkErrorModalAsOpen;
}

// -- error.effects.ts --
@Effect()
launchErrorModal$: Observable<Action> = this.actions$.pipe(
  ofType<LaunchErrorModal>(ErrorActions.LaunchErrorModal),
  withLatestFrom(this.store.pipe(select(fromError.getIsErrorModalOpen))),
  filter
  tap(() => this.dialog.open(ErrorModalComponent))
);