[armchairhacker]

The problem I have when writing JS/TS is that asserting non-null adds verbosity:

Consider the author’s proposed alternative to ‘process.env.MY_ENV_VAR ?? “”’:

    if (process.env.MY_ENV_VAR === undefined) {
     throw new Error("MY_ENV_VAR is not set")
    }

That’s 3 lines and can’t be in expression position.

There’s a terser way: define an ‘unwrap’ function, used like ‘unwrap(process.env.MY_ENV_VAR)’. But it’s still verbose and doesn’t compose (Rust’s ‘unwrap’ is also criticized for its verbosity).

TypeScript’s ‘!’ would work, except that operator assumes the type is non-null, i.e. it’s (yet another TypeScript coercion that) isn’t actually checked at runtime so is discouraged. Swift and Kotlin even have a similar operator that is checked. At least it’s just syntax so easy to lint…