Erroneous "unreachable code" with async IIFE?

[aseemk]

TypeScript Version: 2.0.3

Code:

const sleep = async (ms) => {
    return new Promise((resolve, reject) => {
        setTimeout(resolve, ms);
    });
};

console.log('Kicking off async task...');

(async () => {
    console.log('Sleeping for 10ms...');
    await sleep(10);
    console.log('Going to fail now. What happens?');
    throw new Error();
})();

console.log('Kicked off.');

Expected behavior: compilation succeeds, and runs with the following output:

Kicking off async task...
Sleeping for 10ms...
Kicked off.
Going to fail now. What happens?

Actual behavior: compilation fails:

async.ts(16,1): error TS7027: Unreachable code detected.

[aseemk]

I should have stated explicitly: the unreachable code is referring to the last line:

console.log('Kicked off.');

Which follows the async IIFE.

Btw, the async IIFE is due to the lack of top-level await: tc39/proposal-async-await#9 (comment)

[aseemk]

I found a workaround — which indeed suggests this is a TypeScript compiler bug.

If I simply save the result of the async IIFE to a variable, the code compiles and runs as expected.

const promise = (async () => {
    ...
})();

Of course, I then need to disable TSLint's warning of an unused variable... =)