Null Bool should be checked for null value

[BSteffaniak]

let Bool _showPrefix = null
let Bool showPrefix {
  get {
    return if (_showPrefix != null) {
      _showPrefix
    } else {
      DEFAULT_SHOW_PREFIX
    }
  }
}

should be able to be written as:

let Bool _showPrefix = null
let Bool showPrefix {
  get {
    return if (_showPrefix) {
      _showPrefix
    } else {
      DEFAULT_SHOW_PREFIX
    }
  }
}