We could improve compile-time checks provided by the TypeScript compiler introducing the unreachable function:

export function unreachable(value: never): never {
  throw InternalException.make(`Reached impossible case`, { node: value });
}

It accepts the parameter never, so it could be used to perform a static exhaustiveness checks for switch clauses:

switch (node.kind) {
  case "id":
    // ...
  // other cases
  default:
    unreachable(node);
}

If some of the node kinds are not covered by the case clauses, we'll get a compilation error:

That's quite useful especially to avoid regressions when changing enum types implementations.