TypeScript从枚举创建数组,然后将其用作服务调用的参数

export enum AgeEnum {
    UNDER_18 = 'UNDER_18',
    ABOVE_18 = 'ABOVE_18'
}

那么在我的组件中,我有以下内容:

private ageArray = Object.keys(AgeEnum);

private restrictionsWrapper: RestrictionsWrapper;

constructor(private restrictionsService: RestrictionsService) {
}

ngOnInit(): void {
    this.getRestrictionsForAge(this.ageArray);
}

private getRestrictionsForAge(ages: string[]) {
    for (const age of ages) {
        this.restrictionsService.getRestrictions(age as AgeEnum)
            .subscribe((options) => {
                    this.restrictionsWrapper.restrictions = options.restrictions;
                }, () => {
                    this.restrictionsWrapper.restrictions = null;
                }
            );
    }
}

我的用户界面服务如下所示:

getRestrictions(age: AgeEnum): Observable<RestrictionsWrapper> {
    const params = new HttpParams().set('age', age);
    return this.http.get<RestrictionsWrapper>(BackendRoute.RESTRICTIONS, {params: params});
}

这是我的 RestrictionsWrapper 型号:

export interface RestrictionsWrapper {
    restrictionDocuments: string[];
    blocked: boolean;
}

但我不想有两个单独的方法,在这里我为每个方法传递两个不同的枚举值。我发现一个错误:

Unhandled error occured. TypeError: Cannot set property 'restrictions' of undefined

知道我做错了什么吗?这真的是正确的吗(或良好的实践) this.restrictionsService.getRestrictions(age as AgeEnum) ?