[Here](https://github.com/Flagsmith/flagsmith-js-client/blob/67319456fc1d2eb554547e905d326e5e342baf40/index.d.ts#L46) I read that the callback will be passed an argument of type: ``` { message: string } ``` I've tested this by passing an incorrect API key to `init()` and it led to a runtime exception. Looking at the network response, the type annotation seems incorrect as your API returns: ``` { detail: string } ```