compilePackages: dayjs throws ReferenceError: arguments is not defined at runtime

[proggeramlug]

Perry: origin/main @ a674b6e (v0.5.1167) · macOS arm64
Setup: package compiled natively via perry.compilePackages (perry.allow.compilePackages: ["*"])
Build/run: perry repro.ts -o out && ./out

(Found via an internal real-package stress run — importing the real package and exercising it.)

Bug

Importing dayjs and calling .format()/.add()/.diff() throws ReferenceError: arguments is not defined. Plain arguments usage in a normal function/method works in Perry (verified), so the trigger is a specific form dayjs compiles to (likely arguments inside a nested/arrow/UMD-wrapped function where the binding is lost).

Repro

import dayjs from 'dayjs';

const d = dayjs('2026-06-14');
console.log(d.format('YYYY-MM-DD'), d.add(30, 'day').format('YYYY-MM-DD'), d.diff(dayjs('2026-01-01'), 'day'));

Expected (Node)

2026-06-14 2026-07-14 164

Actual (Perry)

ReferenceError: arguments is not defined