Type Signature Mismatch: getUserId() Function Returns void but Actually Returns userId

Describe the bug

The getUserId() function in the BrowserTracker API returns void according to its type signature, even though the function behaves as expected and actually returns the userId.

To Reproduce

To reproduce this issue, you can look at the API definition for BrowserTracker. The getUserId() function is defined as:

getUserId: () => void;

Expected behavior

I would expect the getUserId() function's type signature to reflect its actual behavior by specifying a return type of string, like so:

getUserId: () => string;

Additional context

While the function itself returns the userId as expected when called, the type signature incorrectly indicates a void return type. This discrepancy could lead to confusion and potential type errors in code that relies on this API.