I'm still using uTorrent 1.8.4 inside WinXP VM. It's what I use for past 10 or so years because it works and still works.
// Never do catch all to assume all non-strings are numbers
if (typeof x === 'number') {
doSomethingForNumber(x)
}
// Per transpiler rule, you not meant to be here, so error throwing is appropriate
throw new Error('Unexpected type')