[cyberax]

You can actually have it built-in (via default case in 'switch' statements having a 'never()' statement). But it's less powerful than Rust's.

[nikeee]

Or you don't use the defualt case and rely on definite assignment analysis or checks for returns in every code path.

I find the never type in TS actually being a proper bottom type + having control-flow based types vastly superior to what rust offers.