I get status 404 with async functions no matter what
Hi all, this is most probably a question not a bug since it's very common but I don't know what's wrong with my code. This is a simple example that results in 404 with `Not Found` default body instead of applying my body and status codes

```
async function AsyncHandler(ctx) {
  ctx.body = await new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve({
        a: 'lol',
        b: 'wut'
      })
    }, 100);
  })  
  ctx.status = 200
}
```

, I have tried many other examples that require async operations like dealing with database and in most cases I get the same thing: 404 with `Not Found`, what's wrong here?


UPDATE: I use this function with koa router