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

2 files changed, 20 insertions, 1 deletions

diff --git a/src/SMAPI/Framework/SCore.cs b/src/SMAPI/Framework/SCore.cs
index bd131762..bfdf1c51 100644
--- a/src/SMAPI/Framework/SCore.cs
+++ b/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
diff --git a/src/SMAPI/Framework/SGame.cs b/src/SMAPI/Framework/SGame.cs
index 89705352..13858fc5 100644
--- a/src/SMAPI/Framework/SGame.cs
+++ b/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)
@@ -458,6 +467,16 @@ namespace StardewModdingAPI.Framework
                 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
                 *********/
                 {