inject.preload.js failing to load a file in chrome from my dev environment

Looks like it is officially broken. The issue is ticketed at https://issues.adblockplus.org/ticket/6744

I tried to debug and find the exact cause, but the issue seems to be elsewhere.
The JS code debugged (inject.preload.js at line 373)

document.documentElement.appendChild(script); // here, script.src is indeed a valid script
document.documentElement.removeChild(script);
URL.revokeObjectURL(url);

The script‘s src attribute targets a valid blob JS which is alive when this line is called!