Thanks for the report!
This would happen the same, whether you Alt+F4 or exit the game; the error message you’ve received is a sanity check to make sure that the game is behaving properly.
In the game’s codebase, an “Advertiser” is an object in the game world which advertises available activities to nearby subscribers. Weapon shops advertise the ability to buy a weapon. NPC Quest-Givers advertise the ability to pick up new quests. Monster zones advertise the ability to come fight monsters.
Each game region has an “Advertiser Manager”, which keeps track of all the advertisers inside that region. In theory, during game shutdown all of the advertisers should remove themselves from the advertiser manager. The error message here is telling us that somehow, when we were destroying those advertiser managers while the game was shutting down, that there was still at least one ‘advertiser’ which hadn’t been destroyed first.
I don’t immediately know what the problem is; this isn’t something I’ve seen before. It’s likely that there’s a subtle bug somewhere. (I immediately wonder if it’s a case of dragging an NPC from one region to another not moving the advertiser registration from the original region’s manager to the new region’s manager).
I’ll do some investigation, once I’ve finished the apartment move that seems to be taking up all my time, at the moment!