Summary

The minifier incorrectly uses the ||= (logical OR assignment) operator when a variable is reassigned within the same conditional block before a property is set on it. This causes a runtime error in strict mode.

JSField - https://jsfiddle.net/h9zt0fa4/1/

Minimal Reproduction

Working code before minification

function loadImage(input) {
    let imageElement = input;
    
    if (!imageElement.src) {
        imageElement = new Image();
        imageElement.src = typeof input === 'string' ? input : URL.createObjectURL(input);
    }
    
    return imageElement;
}
const result = loadImage('https://picsum.photos/200/300');
console.log('Success! Image src:', result.src);

Broken code after minification

function e(e) {
	let t = e;
	return t.src ||= (t = new Image(), typeof e == "string" ? e : URL.createObjectURL(e)), t;
}
const t = e("https://picsum.photos/200/300");
console.log("Success! Image src:", t.src);

The Problem

The ||= operator evaluates as:
t.src = t.src || (t=new Image, typeof e=='string'?e:URL.createObjectURL(e))
Execution order when t is a string 'https://example.com/image.jpg':

1. Capture assignment target: t.src (at this point, t is the string)
2. Evaluate left side: t.src → undefined (accessing .src on string)
3. Since falsy, evaluate right side: (t=new Image, value) - t is reassigned to Image object. Comma operator returns the URL string
4. Execute assignment: Try to set string.src = "https://..."
5. In strict mode (ES modules): TypeError: Cannot create property 'src' on string

Expected Behavior

The minifier should recognize that when:

1. A variable is reassigned inside the conditional expression
2. A property is then set on that variable