Help, cannot compile when I access global state
I am making an App with jester which need access global states.

```nim
import asyncdispatch
import jester

type
  App = ref object
    counter: int

let app = App()

routes:
  get "/count":
    app.counter += 1
    resp $app.counter

runForever()
```

compile error:
```
lib/nim/core/macros.nim(362, 13) Error: type mismatch: got (proc (request: Request, response: Response): Future[system.bool]{.locks: <unknown>.}, Settings)
but expected one of: 
proc serve(match: proc (request: Request; response: Response): Future[bool];
          settings: Settings = newSettings())
```

How can I fix this.