Reduce of empty array with no initial value

[409915016]

Dashboard.vue?98fa:69 Uncaught (in promise) TypeError: Reduce of empty array with no initial value
    at Array.reduce (<anonymous>)
    at eval (Dashboard.vue?98fa:69)

给定 Reduce 函数第二参数 initialValue 为 0 ，避免相册内没有照片导致的报错

this.numbers.photos = albums
    .map((album) => album.photos.length)
    .reduce((a, b) => a + b, 0);