Provider emits 'synced' on close

[mnzaki]

Description
Based on this line which triggers this setter, the provider emits a synced event with { state: false } on close.
This contradicts the expected behavior based on the docs which describe the synced event as:

When the Y.js document is successfully synced (initially).

In general the { state } of a synced event doesn't make sense to me, what does it mean when it is false?

Steps to reproduce the bug

1. Construct a provider with an onSynced handler
2. synced emit on initial sync
3. Close provider
4. synced emitted again

Expected behavior
synced should only be emitted on initial sync