fix(search-pro): fix option customFields not effects

[init-qy]

before

const entries = [
      {
        getter: (page) =>  page.frontmatter.category,
        formatter: {
          '/': '分类：$content',
          '/en/': 'Category: $content',
        },
      }
    ].map(({ formatter }, index) => formatter ? [(index.toString(), formatter)] : null).filter((item) => item !== null)
const obj = Object.fromEntries(entries);
console.log(obj); // Object { [object Object]: undefined }

after

const entries = [
      {
        getter: (page) =>  page.frontmatter.category,
        formatter: {
          '/': '分类：$content',
          '/en/': 'Category: $content',
        },
      }
    ].map(({ formatter }, index) => formatter ? [index.toString(), formatter] : null).filter((item) => item !== null)
const obj = Object.fromEntries(entries);
console.log(obj); // Object { 0: Object { /: "分类：$content", /en/: "Category: $content" } }

[Mister-Hope]

could you revert this?