TypeScript: Disabling unreachable code detection partially for the condition completeness check

I want to disable the unreachable code detection for the condition completeness check.

function f(n) {
  switch(n) {
    case 0: return 0;
    default: return 1;
  }
  // comment base disabling
  // @unreachable
  assert(false); // remove by unassert tools before the release
  throw new Error();
}