Can't to use "id" as a string in the case that it looks like a natural number

I have:

```
"regions": [
    {
      "id": "177",
      "name": "Moscow"
    }
]
```

but the request:

`GET /regions/177`

is empty

If i remove code from test/server/units.js:

```
    } else if (!isNaN(+value)) {
      return +value
    }
```

to:

```
    } else {
      return value
    }
```

it works fine. What is wrong?
