custom UI level switcher does act in accordance with map

[smallTrogdor]

Current Behavior

The custom UI level switcher does not behave well, i.e. it is always displayed, even though there is no level selectable.

Expected Behavior

The custom UI level switcher also only appears, if levels are available in the visible screen area.

Steps To Reproduce

Any environment

On which OS do you experience this bug?

iOS, Android

OS Version

any

Flutter SDK version

any

Anything else

No response