I've already deleted the 'za' folder, updated everything, added the Error Handler, but the error still persists... It only appears when I enter the game and go to check the mailbox. The two mods that show errors are from two mods that have folders that I believe are not used; one is from Toshinori, which has this folder, and the other is a requirement for the NPC Adventure that I heard has been causing issues, so I haven't installed it. The error message is:
An error occurred in the base update loop: IndexOutOfRangeException: Index was outside the bounds of the array. at StardewValley.Quests.Quest.getQuestFromId(Int32 id) in stardewvalley\Farmer\Farmer\Quests\Quest.cs:line 171 at StardewValley.Farmer.addQuest(Int32 questID) in stardewvalley\Farmer\Farmer\Farmer.cs:line 7251 at StardewValley.Menus.LetterViewerMenu..ctor_PatchedBy<Esca.CustomNPCExclusions__PeacefulEnd.FashionSense>(LetterViewerMenu this, String mail, String mailTitle, Boolean fromCollection) at StardewValley.GameLocation.mailbox_PatchedBy<Digus.MailFrameworkMod__Digus.MailServiceMod>(GameLocation this) at StardewValley.GameLocation.performAction_PatchedBy<Esca.EMP__FlashShifter.SVECode__PeacefulEnd.FashionSense__spacechase0.BiggerBackpack__spacechase0.SpaceCore__tlitookilakin.AeroCore>(GameLocation this, String action, Farmer who, Location tileLocation) at StardewValley.GameLocation.checkAction_PatchedBy<DecidedlyHuman.MappingExtensionsAndExtraProperties>(GameLocation this, Location tileLocation, Rectangle viewport, Farmer who) at StardewValley.Locations.BuildableGameLocation.checkAction(Location tileLocation, Rectangle viewport, Farmer who) at StardewValley.Farm.checkAction(Location tileLocation, Rectangle viewport, Farmer who) at StardewValley.Game1.<>c__DisplayClass859_0.<tryToCheckAt>b__0() at MinecartPatcher.MCPModHooks.OnGameLocation_CheckAction(GameLocation location, Location tileLocation, Rectangle viewport, Farmer who, Func`1 action) in D:\Code\NewSDV\SDVFactory\MinecartPatcher\MCPModHooks.cs:line 58 at StardewValley.Game1.tryToCheckAt_PatchedBy<Platonymous.TMXLoader.Entry>(Vector2 grabTile, Farmer who) at StardewValley.Game1.pressActionButton_PatchedBy<tlitookilakin.AeroCore>(KeyboardState currentKBState, MouseState currentMouseState, GamePadState currentPadState) at StardewValley.Game1.<>c__DisplayClass913_0.<UpdateControlInput>b__0() at MinecartPatcher.MCPModHooks.OnGame1_UpdateControlInput(KeyboardState& keyboardState, MouseState& mouseState, GamePadState& gamePadState, Action action) in D:\Code\NewSDV\SDVFactory\MinecartPatcher\MCPModHooks.cs:line 42 at StardewValley.Game1.UpdateControlInput(GameTime time) at StardewValley.Game1._update(GameTime gameTime) at StardewValley.Game1.Update_PatchedBy<StardewValleyUI>(Game1 this, GameTime gameTime) at StardewModdingAPI.Framework.SCore.OnPlayerInstanceUpdating(SGame instance, GameTime gameTime, Action runUpdate)