安装typedoc：

npm install typedoc --save-dev

然后在tsconfig.json中添加typedocOptions：

{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    // ...some lines there
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "es2018",
      "dom"
    ],
    "emitDecoratorMetadata": true
  },
  "angularCompilerOptions": {
    "fullTemplateTypeCheck": true,
    "strictInjectionParameters": true
  },
  "typedocOptions": {
    "mode": "modules",
    "out": "docs"
  }
}

那我就做了

npx typedoc --out docs src/index.ts

并得到错误：

Error: Tried to set an option (mode) that was not declared.

我该怎么解决？