Safari doesn't logout from a chat on refresh

[catap]

An environment:

• Safari 14.1.1 (16611.2.7.1.4) on macOS 11.4 (20F71);
• g8 template with root d72db85933f91a4d9f012ee2d8c643c36c4a40ac.

A step to reproduce:

• create a new project by sbt new UdashFramework/udash.g8;
• start it by sbt compile compileStatics run;
• open safari and go to a page;
• log in;
• refresh a page;
• log in one more time;
• see that number of connected users is 2.

The video:

https://user-images.githubusercontent.com/37775/127490487-5d3cc76f-5457-42f4-b489-33ae97cb3644.mov

The issue doesn't appear on Firefox, but it appears on Safari Technology Preview 127 (Safari 15.0, WebKit 16612.1.18.11.3).

[mereszeta]

This is probably related to poor support of WebSocket in Safari(especially close events). Not sure yet whether it's something we can work around(without much overhead), needs more investigation.

[catap]

@mereszeta let me share a pcap with traffic from safari.

dump.pcap.zip

I've refreshed a page a few times, and before re-login to websocket on backed safari had closed a connection.

I feel that it is a bug in chat application or atmoshere or somewhere else on this stack. Why? Because when connection is closed a counter should be decreased.