Typescript error
Not sure which repo this goes in:

```
node_modules/@types/koa-joi-router/index.d.ts:29:53 - error TS2694: Namespace 'Application' has no exported member 'Next'.

29     type FullHandler = (ctx: Koa.Context, next: Koa.Next) => any;
                                               ~~~~


Found 1 error.
```