With this fix landed, a new bug in clear() has become evident.
As you know, settings .store = ... emits a change event.

The code for clear() is currently as follows:

clear(): void {
	this.store = createPlainObject(); // <-- set store to an empty object, which will in turn emit a change event where current = {}

	for (const key of Object.keys(this.#defaultValues)) {
		this.reset(key); // <-- reset keys, without emitting a change event
	}
}

As you can see, we emit a change event with a blank object, and don't properly emit the post-reset() store.

Noticing this illuminated the following static typing predicament:

suppose we initialize a Conf:

type MyType = { foo: number }
const conf = new Conf<MyType>() // <-- this should require a defaults property with a value of type MyType

Instead of following this, the internal implementation basically always assumes that defaults is a Partial<T> and that the Conf, despite its type being MyType, is actually only Partial<T>. For practical use and type safety, the Conf should statically type to T (MyType in my example), not Partial<T>. If not, and you want to stick with Partial<T> it's critical that

get store()'s method header is rewritten to

get store(): Partial<T>

because either following a reset() or from the very onset with a partial defaults object, the client cannot be sure that the store is of type T.