Target ES2022 + Module CommonJS silently produces code with TypeError in runtime

Bug Report

This bug exists in my project, not only playground, but playground seem to also have bugs, because i can’t even seem to reliably reproduce it in the playground – sometimes it does not react on Target change. But right now i have an opened playground tab with this bug.

I will duplicate the MRE code right here as a text. This is the source code

class Helper {
    create(): boolean {
        return true
    }
}

export class Broken {

    constructor(readonly facade: Helper) {
        console.log(this.bug)
    }
    bug = this.facade.create()

}

new Broken(new Helper)

This is the compiled code with target: ES2022 and module: CommonJS

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Broken = void 0;
class Helper {
    create() {
        return true;
    }
}
class Broken {
    facade;
    constructor(facade) {
        this.facade = facade;
        console.log(this.bug);
    }
    bug = this.facade.create();
}
exports.Broken = Broken;
new Broken(new Helper);

If run this JS – we will get TypeError

Cannot read properties of undefined (reading 'create') 

⏯ Playground Link

Playground link with relevant code

I’m also sharing the playground link, but i assume it could produce the right code for you if you open it first time. To reliable reproduce – change module to Node16 and then to CommonJS. You should see this result

[RyanCavanaugh]

The code generation here is as-expected; the bug is the lack of error message to flag the use-before-init.

[rbuckton]

It looks like our expectation (prior to useDefineForClassFields), was that parameter property initializers are assigned before instance initializers, as evidenced by the emit when useDefineForClassFields is false:

    constructor(facade) {
        this.facade = facade;
        this.bug = this.facade.create();
        console.log(this.bug);
    }

I would contend that the issue is our emit when useDefineForClassFields is true isn’t correctly moving the field initializers into the constructor. Really, the emit should be this:

    facade;
    bug;
    constructor(facade) {
        this.facade = facade;
        this.bug = this.facade.create();
        console.log(this.bug);
    }