Response data and error is null when using --extract-response-body

FWIW, I'm using this Swagger spec to generate an API: https://esi.evetech.net/latest/swagger.json

I then use the following command to generate the API:

```
swagger-typescript-api \
-p https://esi.evetech.net/latest/swagger.json \
-o src/app/api/esi \
--route-types \
--responses \
--extract-enums \
--extract-request-params \
--extract-request-body \
--extract-response-body \
--extract-response-error \
--modular \
--sort-types \
--sort-routes
```

Whenever I try to use `--extract-response-body`, I'm not ever able to access the data attribute. I have confirmed that I'm getting valid data back from `await response.json()`.

```ts
import { Api } from './api'

const api = new Api()

const response = await api.getContractsCharacterIdContracts({ ... })

// These don't work; both always null
// if (response.error) return
// const data = response.data

// This works fine
if (!response.ok) return
const data = await response.data()
```

It's only when I remove the `--extract-response-body` that I'm able to access the `data` and `error` attributes again.

Anything I'm doing wrong or is there something else going on?