Windower hanging on shutdown / returning to POL when addon uses packets API in 'unload' event.

[Imisnew2]

If an addon has registered an unload event, then Windower may hang when returning to POL (e.g. via hitting 'back' from the title screen) or when shutting down (e.g. via the /shutdown text command).

Here is a minimal addon reproducer.

_addon.name = 'Testing'
_addon.author = 'Imisnew'
_addon.commands = {'testing'}
_addon.version = '1.0.0.0'

windower.register_event('unload', function()
    -- Unsure if the packet type is relevant
    windower.packets.inject_incoming(0x052, string.char(0,0,0,0,0,0,0,0))
    windower.packets.inject_incoming(0x052, string.char(0,0,0,0,1,0,0,0))
end)

The steps to reproduce would be:

• Disable all addons and plugins (e.g. only LuaCore is loaded when FFXI starts)
  • I achieved this by editing 'autoload.txt' after logging into POL
• Load this addon
• Either: /shutdown, or /logout followed by backing out of the title screen so that we return to POL.

Some popular addons have code that injects packets on unload, which is how this was discovered.

Note: Other APIs, such as print(...) can also cause Windower to either hang or crash (with a C++ runtime error), but these were not observed to reliably cause Windower to hang or crash.