auto-fix save data when a custom location mod is removed

docs/README.md

@@ -25,8 +25,8 @@ doesn't change any of your game files. It serves eight main purposes:
    possible to troubleshoot errors in the game itself that would otherwise show a generic 'program
    has stopped working' type of message._
 
-   _That also includes automatically fixing save data when a load would crash, e.g. due to a custom
-   NPC mod the player removed._
+   _SMAPI also automatically fixes save data in some cases when a load would crash, e.g. due to a
+   custom location or NPC mod that was removed._
 
 6. **Provide update checks.**  
    _SMAPI automatically checks for new versions of your installed mods, and notifies you when any

docs/release-notes.md

@@ -13,7 +13,7 @@ For players:
   SMAPI should have less impact on game performance and startup time for some players.
 
 * **Added more error recovery.**  
-  SMAPI now detects and prevents more crashes due to game or mod bugs, or due to removing some mods which add custom content.
+  SMAPI now detects and prevents more crashes due to game/mod bugs, or due to removing mods which add custom locations or NPCs.
 
 * **Improved mod scanning.**  
   SMAPI now supports some non-standard mod structures automatically, improves compatibility with the Vortex mod manager, and improves various error/skip messages related to mod loading.
@@ -46,7 +46,7 @@ For modders:
   * Improved mod scanning:
     * Now ignores metadata files and folders (like `__MACOSX` and `__folder_managed_by_vortex`) and content files (like `.txt` or `.png`), which avoids missing-manifest errors in some common cases.
     * Now detects XNB mods more accurately, and consolidates multi-folder XNB mods in logged messages.
-  * SMAPI now automatically fixes your save if you remove a custom NPC mod. (Invalid NPCs are now removed on load, with a warning in the console.)
+  * SMAPI now automatically removes invalid content when loading a save to prevent crashes. A warning is shown in-game when this happens. This applies for locations and NPCs.
   * Added support for configuring console colors via `smapi-internal/config.json` (intended for players with unusual consoles).
   * Improved launch script compatibility on Linux (thanks to kurumushi and toastal!).
   * Save Backup now works in the background, to avoid affecting startup time for players with a large number of saves.

src/SMAPI/Framework/SCore.cs

@@ -245,7 +245,7 @@ namespace StardewModdingAPI.Framework
                     new DialogueErrorPatch(this.MonitorForGame, this.Reflection),
                     new ObjectErrorPatch(),
                     new LoadContextPatch(this.Reflection, this.GameInstance.OnLoadStageChanged),
-                    new LoadErrorPatch(this.Monitor)
+                    new LoadErrorPatch(this.Monitor, this.GameInstance.OnSaveContentRemoved)
                 );
 
                 // add exit handler

src/SMAPI/Framework/SGame.cs

@@ -65,6 +65,9 @@ namespace StardewModdingAPI.Framework
         /// <remarks>Skipping a few frames ensures the game finishes initializing the world before mods try to change it.</remarks>
         private readonly Countdown AfterLoadTimer = new Countdown(5);
 
+        /// <summary>Whether custom content was removed from the save data to avoid a crash.</summary>
+        private bool IsSaveContentRemoved;
+
         /// <summary>Whether the game is saving and SMAPI has already raised <see cref="IGameLoopEvents.Saving"/>.</summary>
         private bool IsBetweenSaveEvents;
 
@@ -216,6 +219,12 @@ namespace StardewModdingAPI.Framework
             this.Events.ModMessageReceived.RaiseForMods(new ModMessageReceivedEventArgs(message), mod => mod != null && modIDs.Contains(mod.Manifest.UniqueID));
         }
 
+        /// <summary>A callback invoked when custom content is removed from the save data to avoid a crash.</summary>
+        internal void OnSaveContentRemoved()
+        {
+            this.IsSaveContentRemoved = true;
+        }
+
         /// <summary>A callback invoked when the game's low-level load stage changes.</summary>
         /// <param name="newStage">The new load stage.</param>
         internal void OnLoadStageChanged(LoadStage newStage)
@@ -457,6 +466,16 @@ namespace StardewModdingAPI.Framework
                 this.Watchers.Reset();
                 WatcherSnapshot state = this.WatcherSnapshot;
 
+                /*********
+                ** Display in-game warnings
+                *********/
+                // save content removed
+                if (this.IsSaveContentRemoved && Context.IsWorldReady)
+                {
+                    this.IsSaveContentRemoved = false;
+                    Game1.addHUDMessage(new HUDMessage(this.Translator.Get("warn.invalid-content-removed"), HUDMessage.error_type));
+                }
+
                 /*********
                 ** Pre-update events
                 *********/

src/SMAPI/Patches/LoadErrorPatch.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
@@ -20,6 +21,9 @@ namespace StardewModdingAPI.Patches
         /// <summary>Writes messages to the console and log file.</summary>
         private static IMonitor Monitor;
 
+        /// <summary>A callback invoked when custom content is removed from the save data to avoid a crash.</summary>
+        private static Action OnContentRemoved;
+
 
         /*********
         ** Accessors
@@ -33,9 +37,11 @@ namespace StardewModdingAPI.Patches
         *********/
         /// <summary>Construct an instance.</summary>
         /// <param name="monitor">Writes messages to the console and log file.</param>
-        public LoadErrorPatch(IMonitor monitor)
+        /// <param name="onContentRemoved">A callback invoked when custom content is removed from the save data to avoid a crash.</param>
+        public LoadErrorPatch(IMonitor monitor, Action onContentRemoved)
         {
             LoadErrorPatch.Monitor = monitor;
+            LoadErrorPatch.OnContentRemoved = onContentRemoved;
         }
 
 
@@ -58,6 +64,22 @@ namespace StardewModdingAPI.Patches
         /// <returns>Returns whether to execute the original method.</returns>
         private static bool Before_SaveGame_LoadDataToLocations(List<GameLocation> gamelocations)
         {
+            bool removedAny = false;
+
+            // remove invalid locations
+            foreach (GameLocation location in gamelocations.ToArray())
+            {
+                if (location is Cellar)
+                    continue; // missing cellars will be added by the game code
+
+                if (Game1.getLocationFromName(location.name) == null)
+                {
+                    LoadErrorPatch.Monitor.Log($"Removed invalid location '{location.Name}' to avoid a crash when loading save '{Constants.SaveFolderName}'. (Did you remove a custom location mod?)", LogLevel.Warn);
+                    gamelocations.Remove(location);
+                    removedAny = true;
+                }
+            }
+
             // get building interiors
             var interiors =
                 (
@@ -83,11 +105,15 @@ namespace StardewModdingAPI.Patches
                         {
                             LoadErrorPatch.Monitor.Log($"Removed invalid villager '{npc.Name}' to avoid a crash when loading save '{Constants.SaveFolderName}'. (Did you remove a custom NPC mod?)", LogLevel.Warn);
                             location.characters.Remove(npc);
+                            removedAny = true;
                         }
                     }
                 }
             }
 
+            if (removedAny)
+                LoadErrorPatch.OnContentRemoved();
+
             return true;
         }
     }

src/SMAPI/i18n/default.json

@@ -1,3 +1,3 @@
 {
-
+    "warn.invalid-content-removed": "Invalid content was removed to prevent a crash (see the SMAPI console for info)."
 }