fix event error in rare cases

2 files changed, 8 insertions, 3 deletions

diff --git a/docs/release-notes.md b/docs/release-notes.md
index 3dee3705..35f711fb 100644
--- a/docs/release-notes.md
+++ b/docs/release-notes.md
@@ -1,4 +1,8 @@
 # Release notes
+## 2.5.1
+* For players:
+  * Fixed event error in rare cases.
+
 ## 2.5
 * For players:
   * **Added support for [content packs](https://stardewvalleywiki.com/Modding:Content_packs)**.  
diff --git a/src/SMAPI/Framework/Events/ManagedEventBase.cs b/src/SMAPI/Framework/Events/ManagedEventBase.cs
index cc4d89ec..7e42d613 100644
--- a/src/SMAPI/Framework/Events/ManagedEventBase.cs
+++ b/src/SMAPI/Framework/Events/ManagedEventBase.cs
@@ -55,7 +55,7 @@ namespace StardewModdingAPI.Framework.Events
         protected void AddTracking(TEventHandler handler, IEnumerable<TEventHandler> invocationList)
         {
             this.SourceMods[handler] = this.ModRegistry.GetFromStack();
-            this.CachedInvocationList = invocationList.ToArray();
+            this.CachedInvocationList = invocationList?.ToArray() ?? new TEventHandler[0];
         }
 
         /// <summary>Remove tracking for an event handler.</summary>
@@ -63,8 +63,9 @@ namespace StardewModdingAPI.Framework.Events
         /// <param name="invocationList">The updated event invocation list.</param>
         protected void RemoveTracking(TEventHandler handler, IEnumerable<TEventHandler> invocationList)
         {
-            this.SourceMods.Remove(handler);
-            this.CachedInvocationList = invocationList.ToArray();
+            this.CachedInvocationList = invocationList?.ToArray() ?? new TEventHandler[0];
+            if(!this.CachedInvocationList.Contains(handler)) // don't remove if there's still a reference to the removed handler (e.g. it was added twice and removed once)
+                this.SourceMods.Remove(handler);
         }
 
         /// <summary>Log an exception from an event handler.</summary>