ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
System.ThrowHelper.ThrowArgumentOutOfRangeException (System.ExceptionArgument argument, System.ExceptionResource resource) (at <a1e9f114a6e64f4eacb529fc802ec93d>:0)
System.ThrowHelper.ThrowArgumentOutOfRangeException () (at <a1e9f114a6e64f4eacb529fc802ec93d>:0)
WarpModMenu+WarpContainer.GenerateRoomButtons (System.Collections.Generic.List`1[T] roomList, WarpModMenu+SortType sort, WarpModMenu+ViewType view) (at <a8476eaab9a141fe8a7366214f4006ed>:0)
UnityEngine.Debug:LogException(Exception)
WarpContainer:GenerateRoomButtons(List`1, SortType, ViewType)
WarpContainer:.ctor(Menu, MenuObject, Vector2, Vector2)
WarpModMenu:WarpInit(RainWorldGame, PauseMenu)
WarpModMenu:PauseMenu_ctor(orig_ctor, PauseMenu, ProcessManager, RainWorldGame)
DMD<>?499257600:Hook<Menu.PauseMenu::.ctor>?1102002176(PauseMenu, ProcessManager, RainWorldGame)
RainWorldGame:Update()
MainLoopProcess:RawUpdate(Single)
RainWorldGame:RawUpdate(Single)
ProcessManager:Update(Single)
DMD<Update>?499257600:_RainWorld::Update(RainWorld)
DMD<>?499257600:Trampoline<RainWorld::Update>?1637448704(RainWorld)
Guardian.LogHooks:RainWorld_Update(orig_Update, RainWorld) (at E:/RainWorldModding/Guardian/src/plugin/Hooks/LogHooks.cs:70)
DMD<>?499257600:Hook<RainWorld::Update>?2073069056(RainWorld)
DMD<>?499257600:Trampoline<RainWorld::Update>?1106297344(RainWorld)
HealthBars.HealthBars:UpdatePatch(orig_Update, RainWorld)
DMD<>?499257600:Hook<RainWorld::Update>?220583936(RainWorld)
DMD<>?499257600:Trampoline<RainWorld::Update>?-933265920(RainWorld)
BeastMaster.BeastMaster:RainWorldOnUpdate(orig_Update, RainWorld)
DMD<>?499257600:Hook<RainWorld::Update>?1878901248(RainWorld)

InvalidOperationException: Sequence contains no elements
at System.Linq.Enumerable.Last[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x00061] in <55b3683038794c198a24e8a1362bfc61>:0
at WarpStats..ctor (Menu.Menu menu, Menu.MenuObject owner) [0x000c0] in <a8476eaab9a141fe8a7366214f4006ed>:0
at WarpModMenu+WarpContainer..ctor (Menu.Menu menu, Menu.MenuObject owner, UnityEngine.Vector2 pos, UnityEngine.Vector2 size) [0x00850] in <a8476eaab9a141fe8a7366214f4006ed>:0
at WarpModMenu.WarpInit (RainWorldGame game, Menu.PauseMenu self) [0x000ea] in <a8476eaab9a141fe8a7366214f4006ed>:0
at WarpModMenu.PauseMenu_ctor (On.Menu.PauseMenu+orig_ctor orig, Menu.PauseMenu self, ProcessManager manager, RainWorldGame game) [0x0000f] in <a8476eaab9a141fe8a7366214f4006ed>:0
at DMD<>?499257600.Hook<Menu.PauseMenu::.ctor>?1102002176 (Menu.PauseMenu , ProcessManager , RainWorldGame ) [0x0000a] in <d212024b52d24b9bb94c417d0106b25a>:0
at RainWorldGame.Update () [0x00228] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at MainLoopProcess.RawUpdate (System.Single dt) [0x0001a] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at RainWorldGame.RawUpdate (System.Single dt) [0x00754] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at ProcessManager.Update (System.Single deltaTime) [0x001ae] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at DMD<Update>?499257600._RainWorld::Update (RainWorld this) [0x01629] in <c34055d92b7444ca9a647e80eba9c225>:0
at DMD<>?499257600.Trampoline<RainWorld::Update>?1637448704 (RainWorld ) [0x00020] in <85eb41678e6a4920af258a61fcc14bfd>:0
at Guardian.LogHooks.RainWorld_Update (On.RainWorld+orig_Update orig, RainWorld self) [0x00002] in E:\RainWorldModding\Guardian\src\plugin\Hooks\LogHooks.cs:70
UnityEngine.StackTraceUtility:ExtractStringFromException(Object)
Guardian.CloudLogger:LogAndUploadException(Exception) (at E:\RainWorldModding\Guardian\src\plugin\CloudLogger.cs:30)
Guardian.LogHooks:RainWorld_Update(orig_Update, RainWorld) (at E:\RainWorldModding\Guardian\src\plugin\Hooks\LogHooks.cs:74)
DMD<>?499257600:Hook<RainWorld::Update>?2073069056(RainWorld)
DMD<>?499257600:Trampoline<RainWorld::Update>?1106297344(RainWorld)
HealthBars.HealthBars:UpdatePatch(orig_Update, RainWorld)
DMD<>?499257600:Hook<RainWorld::Update>?220583936(RainWorld)
DMD<>?499257600:Trampoline<RainWorld::Update>?-933265920(RainWorld)
BeastMaster.BeastMaster:RainWorldOnUpdate(orig_Update, RainWorld)
DMD<>?499257600:Hook<RainWorld::Update>?1878901248(RainWorld)


InvalidOperationException: Sequence contains no elements
System.Linq.Enumerable.Last[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <55b3683038794c198a24e8a1362bfc61>:0)
WarpStats..ctor (Menu.Menu menu, Menu.MenuObject owner) (at <a8476eaab9a141fe8a7366214f4006ed>:0)
WarpModMenu+WarpContainer..ctor (Menu.Menu menu, Menu.MenuObject owner, UnityEngine.Vector2 pos, UnityEngine.Vector2 size) (at <a8476eaab9a141fe8a7366214f4006ed>:0)
WarpModMenu.WarpInit (RainWorldGame game, Menu.PauseMenu self) (at <a8476eaab9a141fe8a7366214f4006ed>:0)
WarpModMenu.PauseMenu_ctor (On.Menu.PauseMenu+orig_ctor orig, Menu.PauseMenu self, ProcessManager manager, RainWorldGame game) (at <a8476eaab9a141fe8a7366214f4006ed>:0)
DMD<>?499257600.Hook<Menu.PauseMenu::.ctor>?1102002176 (Menu.PauseMenu , ProcessManager , RainWorldGame ) (at <d212024b52d24b9bb94c417d0106b25a>:0)
RainWorldGame.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
MainLoopProcess.RawUpdate (System.Single dt) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
RainWorldGame.RawUpdate (System.Single dt) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
ProcessManager.Update (System.Single deltaTime) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
DMD<Update>?499257600._RainWorld::Update (RainWorld this) (at <c34055d92b7444ca9a647e80eba9c225>:0)
DMD<>?499257600.Trampoline<RainWorld::Update>?1637448704 (RainWorld ) (at <85eb41678e6a4920af258a61fcc14bfd>:0)
Guardian.LogHooks.RainWorld_Update (On.RainWorld+orig_Update orig, RainWorld self) (at E:/RainWorldModding/Guardian/src/plugin/Hooks/LogHooks.cs:70)
UnityEngine.Debug:LogException(Exception)
Guardian.CloudLogger:LogAndUploadException(Exception) (at E:/RainWorldModding/Guardian/src/plugin/CloudLogger.cs:31)
Guardian.LogHooks:RainWorld_Update(orig_Update, RainWorld) (at E:/RainWorldModding/Guardian/src/plugin/Hooks/LogHooks.cs:74)
DMD<>?499257600:Hook<RainWorld::Update>?2073069056(RainWorld)
DMD<>?499257600:Trampoline<RainWorld::Update>?1106297344(RainWorld)
HealthBars.HealthBars:UpdatePatch(orig_Update, RainWorld)
DMD<>?499257600:Hook<RainWorld::Update>?220583936(RainWorld)
DMD<>?499257600:Trampoline<RainWorld::Update>?-933265920(RainWorld)
BeastMaster.BeastMaster:RainWorldOnUpdate(orig_Update, RainWorld)
DMD<>?499257600:Hook<RainWorld::Update>?1878901248(RainWorld)

active mods list:
Needle cleanup
Arena slugcats configurator
LoadTimeFix
Dev toools
Alpha tracks in arena
OSHA compliant gates
OSHA compliant shelters
Spearmaster pearl storage
Add inv to campaign select
Yeek fix
Unlocked saint
Visible ID
No arena grab death
Mod presets
BeastMaster
Merge Fix
Less Deadly Rain
Health bars
Guardian
Gill issue
Friends of Friends
Expedition
Dress My Slugcat
Dev console
Pups+ (main suspect)
Warp menu (Obviously)
More slugcats expansion
Rain world remix
Lancer
Slugbase
Catsupplement

(this bug has also occured to me when playing as wingcat with a couple of different custom regions enabled, but i forget the exact mods i had enabled at the time.)

Update: I tested it and pups+ is not the issue, at least one region (shoreline) is broken regardless. going to disable all mods but the pre-packaged ones and warp menu, and see if that fixes it.

Update to the update: Even with only pre-packaged mods, shoreline still broke.

Wooohoo im not the only one

Haven't been able to get to the bottom of this yet but its tied to the subregion colors. If you make sure your SORT | VIEW options are set to either size or type it should prevent this issue while I try and fix it.

This should now be fixed with the latest update (1.84.7)

it does not work still