TypeError：减少没有初始值的空数组

Question

我正试图在我的角度4应用程序中显示总和。我已经实现了以下代码，但它给了我错误

结构

filename

将数组初始化为以下值

export interface NpvResults  {

            captiveInsYear: number[];
            captiveInsPremiumPaid: number[];
            captiveInsTaxDeduction: number[];
            captiveInsLoanToParent: number[];
            captiveInsCapitalContribution: number[];
            captiveDividentDistribution: number[];
            captiveInsTerminalValue: number[];

        }

TypeError：减少没有初始值的空数组

this.sourceResults.captiveInsPremiumPaid = [1,2,3,4,5];

然后在组件中

{{NpvResults?.captiveInsPremiumPaid.reduce(sum) | number:'.0-3'}}