[Crash]: Crash after kicking spectator

[WenSimEHRP]

Version of OpenTTD

20240510-master-ga5c2543efc, Windows 11

Steps to reproduce

1. Start a new server
2. let another client join the server and then join or found a new company
3. kick the player
   
4. notice "spectators" is kickable and kick spectators
   
5. Crash!

Upload crash files

crash.zip

[rubidium42]

Also reproducible in 14.1.

What seems to be the problem is twofold.

1. The client lists caches the buttons that are available and what they can do.
2. Due to deferred deletion of the client, the window invalidation is still done when the client object exists. So at row 3 there's still a client when the button lists are rebuilt, but once it has gone away that becomes the row with the spectator 'company' line.