typescript定义namespace一个后，在使用webpack打包时如何处理

Question

1. 现在有一个全局对象gapi通过script标签在dom中引入，环境：react+typescript+webpack

2. 示例代码及已经做过的尝试如下

   // gapi.d.ts
   declare namespace gapi {
       ...
   }
   
   // index.tsx
   ...
   // 打包时写成这样会报错 Property 'gapi' does not exist on type 'Window'.
   window.gapi.load('auth2', function(): void{
       auth2 = window.gapi.auth2.init({
         client_id: `${config.googleClientId}.apps.googleusercontent.com`,
         cookie_policy: 'single_host_origin',
       });
       attachSignin(document.querySelector(selector));
     });
   
   // 以下代码可以打包通过，但是gapi的类型变为any
   (window as any).gapi.load('auth2', function(): void{
       auth2 = (window as any).gapi.auth2.init({
         client_id: `${config.googleClientId}.apps.googleusercontent.com`,
         cookie_policy: 'single_host_origin',
       });
       attachSignin(document.querySelector(selector));
     });
   
   ...

3. 请问如何才能两全其美，既不丢失gapi的类型，又能打包通过