Background.exit() cannot be Array<Number>

When trying to pass an Array of Numbers to Background.exit()

Background.exit([1,2,3] as Array<Number>);

I get the following error:

Invalid 'Array<Number>' passed as parameter 1 of type
'PolyType<Null or Array<Application.PropertyValueType> or Boolean or Char or Dictionary<Boolean or Char or Double or Float or Long or Number or String,Application.PropertyValueType> or Double or Float or Long or Number or String or WatchUi.BitmapResource>'

But, the PolyType allows Array<Application.PropertyValueType> and PropertyValueType can be a Number. So, I don't understand why this fails.

When I set the compiler from -l 1 to -l 0, it compiles and works fine. Is this a compiler bug? Can I set the type checking option to zero around this one statement? I strongly desire to have type checking turned on to the max (-l 3) and this is the only issue that I haven't ben able to figure out in several hundreds of lines of code on multiple projects.