Repeated handshakes on outdated clients

[dlqqq]

The SS1 + SS2 handshake constantly repeats when you:

1. Have an existing client (browser tab) open
2. Restart the server without closing the existing client

The existing client that connected to the previous server session will constantly re-open the WS and retry the SS1 + SS2 handshake.

[dlqqq]

Ah, the constant retries were because I was opening a 10+ MiB YDoc, so the SS2 message sent by the client was being auto-rejected by the server with error code 1009 (message too big).

With smaller files, the behavior is different: the content gets doubled because the client's YDoc has a different history than the server's YDoc after restart. Yjs then merges the two by effectively doubling the content.