Koans online task #32 returns Internal Server Error

Support
4

Your code is invalid. It will cause a stack overflow (the setter recursively calls itself). You should use the field identifier to access the property’s storage.

var propertyWithCounter: Int? = null
    set(value:Int?) {
        counter++
        field = value
    }

Given this, the error message is not helpful. Something that provides better diagnostics would be very helpful.