问错误TypeError:当试图使用缓存获取详细信息时，无法读取未定义属性的“映射”

EN

  private ProductsCache: any[] = [];

  getAllProducts(accountId: string): Observable<any[]> {
    return this.ProductsApiService.GetAllProducts(accountId, false).map((Products) => {
      this.ProductsCache = Products;
      return Products;
    });
  }

  getProductDetailsById(id: number): Observable<any> {
    if(this.ProductsCache.length < 1) {
      this.getAllProducts(this.AccountApiService.getAccountId()).subscribe((Products: any) => { 
        let ProductDetails = Products.find(x => x.id === Number(id));
        return Observable.of(ProductDetails);
      });
    } else{
      let ProductDetails = this.ProductsCache.find(x => x.id === Number(id));
      return Observable.of(ProductDetails);
    }
  }