When a player attempts to equip a tool while respawning the client shuts down. This affects any user on a windows system that I’ve spoken to (unable to test other systems). Potentially related to some of the complaints here.
The bug occurs every time a player respawns from what I can tell. To recreate, you can go here and reset. To get the “This game has shut down” message, rapidly press a key to equip a tool before your new character loads in. This occurs regardless of filtering enabled status and is caused by equipping the tool before the new character loads. This can be tested by putting a tool in slot 8 of the place linked and using that to shut down the client, whereas I was unable to shut down my client by leaving slot 1 empty and rapidly trying to equip that as the character respawned. This leads me to believe it is caused by whatever handles removing old tools as a new character is loaded in.
It’s a very short window of opportunity to trigger the bug, I recommend using a macro if you have trouble reproducing it.
Please let me know if any more information is required.