yes, I mean how default is treated different here:

import x from "path"
And
const x = v;

compared to here:

import {x} from "path"
and
const {x} = v;

export * from "./mod.mjs";
import * as NS from "./mod.mjs";
export default NS.default ?? "💥";

export * from "./mod.mjs";
import * as NS from "./mod.mjs";
export default NS.default ?? "nothing to see here";

export function then(cb) {
    cb({
         ...Object.fromEntries(Object.keys(NS).filter((n) => n !== 'default').map(n => [n, NS[n]])),
        get default() {
            if ('default' in NS) return NS.default;
            throw new Error("not the module you were looking for");
        }
    });
}

I saw that you released 12.0.1; thanks for your hard work.
FYI: I’m still getting some warnings even with a biblio file.

That is: I tried upgrading ecmarkup to 12.0.1, running ecmarkup --verbose --write-biblio biblio-decorators.json spec.html > /dev/null in ecma262’s #2417 branch (“decorators”), moved biblio-decorators.json to the pipe operator’s #268 branch (“at-sign”), and then (in that pipe branch) ran ecmarkup --verbose spec.html --load-biblio ./biblio-decorators.json dist/index.html.

The biblio file is definitely doing something; without it I also get a bunch of extra “can't find clause, production, note or example with id” warnings.
But it’s still giving me “could not find definition corresponding to production Decorator” warnings; I’m not sure why.