User authentication

That was my thought initially, but I've tried this and an exception is thrown. To me, it's the logical place to do this, but the exception is thrown by a system file:

Code:

    "title": "ErrorException",
    "type": "ErrorException",
    "code": 500,
    "message": "Undefined property: App\\Filters\\ApiBaseFilter::$response",
    "file": "\\vendor\\codeigniter4\\framework\\system\\API\\ResponseTrait.php",
    "line": 128,

This seems to be looking for a $response in the filter, but because it's the before function, there's only a request.

I have found a workaround, but I'm wondering if this is intended behaviour? And if it is, how should the API Response Trait actually be used?