Regression with keepalive: false in version 9.1.1 (from version 5.0.5)

[joudinet]

Describe the bug
Moving from version 5.0.5 to 9.1.1, users connected to a MUC room do not leave the room anymore when the browser tab is closed. Thus, if they try to reconnect using the same nickname, they got the following error message:

The nickname you chose is reserved or currently in use, please choose a different one.

To Reproduce
Steps to reproduce the behavior:

1. Here the configuration I use for converse 9.1.1:

	"allow_contact_requests": false,
	"allow_logout": false,
	"allow_muc_invitations": false,
	"allow_user_trust_override": "off",
	"assets_path": "/conversejs/",
	"authentication": "anonymous",
	"auto_login": true,
	"auto_join_rooms": [ "forum@conference.example.com" ],
	"clear_cache_on_logout": true,
	"discover_connection_methods": false,
	"hide_muc_server": true,
	"jid": "example.com",
	"keepalive": false,
	"loglevel": "debug",
	"message_archiving": "never",
	"muc_disable_slash_commands": true,
	"notify_all_room_messages": [ "forum@conference.example.com" ],
	"persistent_store": "sessionStorage",
	"play_sounds": true,
	"sounds_path": "/conversejs/sounds/",
	"strict_plugin_dependencies": false,
	"singleton": true,
	"view_mode": "embedded",
	"websocket_url": "wss://example.com/ws/"

It is almost the same the configuration as for converse 5.0.5. I've just replaced the trusted: "off" option by allow_user_trust_override: "off", clear_cache_on_logout: true, and persistent_store: "sessionStorage" options.

2. Log in to an ejabberd 20.07 server, which is configured to accept websocket connection as anonymous users.
3. Log out (by closing the tab or changing the address).
4. Try to log in again with the same nickname.

Expected behavior
As keepalive is set to false, it should be possible to rejoin the same MUC room with the previous nickname, and it was working with converse 5.0.5.

Environment

• Desktop
• Chromium 101 and Firefox 100
• Converse.js version 9.1.1

[joudinet]

I found out the issue : it is in the documentation. It says enable_smacks is by default at false but it isn't. Setting the enable_smacks option to false fixes my issue.