web.indexed_db: is `'read-write'` correct `mode` for `transaction`, or a mistake?

Hello,

In the source code, at [`~/hive/backend/js/web_worker.dart`](https://github.com/hivedb/hive/blob/master/hive/lib/src/backend/js/web_worker/web_worker.dart#L228),
`'read-write'` is being passed to `IDBDatabase.transaction(` function, which is,
- Neither mentioned at [MDN.IDBDatabase.transaction.parameters](https://developer.mozilla.org/en-US/docs/Web/API/IDBDatabase/transaction#parameters),
- Nor found anywhere else in the source code, but, `'readwrite'` is, and is also mentioned in the docs.

**Question**
Is this behavior correct, or a mistype?

Thanking you,