I clicked on the "world" tab just as a caravan was arriving at an event and got the following message.
Called DrawWorldLayers() but already regenerating. This shouldn't ever happen because LongEventHandler should have stopped us.
Full log below
Loading game from file Ghostly with mods Core, 1438693028, 1414907955, 1420241138, 1421806244, RimFridge, A_Dog_Said_1.0, 1454228967, 1442879524
Verse.Log:Message(String, Boolean) (at C:\Dev\RimWorld\Assets\Scripts\Verse\Utility\Debug\Log\Log.cs:49)
Verse.SavedGameLoaderNow:LoadGameFromSaveFileNow(String) (at C:\Dev\RimWorld\Assets\Scripts\Verse\Map\MapIniter\SavedGameLoaderNow.cs:19)
Verse.Root_Play:<Start>m__0() (at C:\Dev\RimWorld\Assets\Scripts\Verse\Global\Root\Root_Play.cs:46)
Verse.LongEventHandler:RunEventFromAnotherThread(Action) (at C:\Dev\RimWorld\Assets\Scripts\Verse\Global\LongEventHandler.cs:455)
Verse.LongEventHandler:<UpdateCurrentAsynchronousEvent>m__1() (at C:\Dev\RimWorld\Assets\Scripts\Verse\Global\LongEventHandler.cs:367)
Called DrawWorldLayers() but already regenerating. This shouldn't ever happen because LongEventHandler should have stopped us.
Verse.Log:Error(String, Boolean) (at C:\Dev\RimWorld\Assets\Scripts\Verse\Utility\Debug\Log\Log.cs:78)
RimWorld.Planet.WorldRenderer:DrawWorldLayers() (at C:\Dev\RimWorld\Assets\Scripts\RimWorld\Planet\Rendering\WorldRenderer.cs:134)
RimWorld.Planet.World:WorldUpdate() (at C:\Dev\RimWorld\Assets\Scripts\RimWorld\Planet\World.cs:230)
Verse.Game:UpdatePlay() (at C:\Dev\RimWorld\Assets\Scripts\Verse\Game\Game.cs:520)
Verse.Root_Play:Update() (at C:\Dev\RimWorld\Assets\Scripts\Verse\Global\Root\Root_Play.cs:99)
Bugs that appear in savegames where you use mods are not prioritized on this thread, please post these bugs on their respective bugthreads under mods.
Bump.
Haven't been able to reproduce, seems like it's a mod-issue or already fixed. Thanks for reporting anyways! ;)