It works fine in the JS Playground.
looking into that
The AxesViewer is part of the Debug namespace, so you need to use BABYLON.Debug.AxesViewer. For a back-compat issue it is also part of the global namespace, but typescript is still expecting the definition to work correctly.
Thanks for the info @RaananW
The docs may need updating Display Axes | Babylon.js Documentation . I can do that.