An exception as an alternative to expectNever()

[rauschma]

class UnsupportedValueError extends Error {
  constructor(value: never, message = `Unsupported value: ${value}`) {
    super(message)
  }
}

// Usage example:
enum Color {Red, Green}
function colorToString(color: Color) {
  switch (color) {
    case Color.Red:
      return 'RED';
    case Color.Green:
      return 'GREEN';
    default:
      throw new UnsupportedValueError(color);
  }
}

I find this code a little more self-explanatory. Compare:

function colorToString(color: Color) {
  switch (color) {
    case Color.Red:
      return 'RED';
    case Color.Green:
      return 'GREEN';
    default:
      return expectNever(color);
  }
}