Async / Await Refactoring - Catch Block Parameter are not checked for collisions

[elizabethdinella]

Search Terms:
Async, Await, Refactoring, Code Fix,

Code

function f() {
	return Promise.resolve().then(x => 1).catch(x => "a").then(x => !!x); 
}

Expected behavior:
The refactor generates the following code with a unique catch parameter.

async function f() {
	let x_1: string | number;
    try {
        const x = await Promise.resolve();
        x_1 = 1;
    }
    catch (x_2) {
        x_1 = "a";
    }
    return !!x_1; 
}

Actual behavior:
The refactor generates the following code with a conflicting catch parameter. "a" is not assigned to the correct x_1.

async function f() {
	let x_1: string | number;
    try {
        const x = await Promise.resolve();
        x_1 = 1;
    }
    catch (x_1) {
        x_1 = "a";
    }
    return !!x_1; 
}

Playground Link:

Related Issues: