TS 3.7: optional chaining output is introducing a local variable

TypeScript Version: 3.7.x-dev.201xxxxx

Search Terms:
optional chaining

Code

function isTrue(something: { value: boolean} | undefined): boolean {
	return something?.value === true; 
}

Expected behavior:
Output:

"use strict";
function isTrue(something) {
    return (something === null || something === void 0 ? void 0 : something.value) === true;
}

Actual behavior:
Actual Output:

"use strict";
function isTrue(something) {
    var _a;
    return ((_a = something) === null || _a === void 0 ? void 0 : _a.value) === true;
}

Reproduce the provided optional-chaining example with the TypeScript 3.7 development compiler and trace the compiler's optional-chaining output path. Done means the emitted JavaScript matches the expected output without introducing the extra local variable, with coverage for this example.