Just have default throw an error? Then, if you add a value to the string union (hopefully) your tests will highlight it isnt handled.

Equally, for such a simple switch, surely a map is better?
But i rarely find myself using switches.
I find ifs with early returns cleaner. Allows for variable creation during execution (which my tslint complains about)

There is support for this in Effect as another implementation.

https://effect.website/docs/guides/style/pattern-matching

I haven't had a chance to try it myself yet. I saw someone give a recommendation for ts-pattern which provides functions for pattern matching with optional exhaustion.