fix errors caused by content managers finalizing asynchronously

src/StardewModdingAPI/Framework/SContentManager.cs

@@ -127,10 +127,13 @@ namespace StardewModdingAPI.Framework
         /// <summary>Get whether the content manager has already loaded and cached the given asset.</summary>
         /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
         public bool IsLoaded(string assetName)
+        {
+            lock (this.Cache)
             {
                 assetName = this.NormaliseAssetName(assetName);
                 return this.IsNormalisedKeyLoaded(assetName);
             }
+        }
 
         /// <summary>Load an asset that has been processed by the content pipeline.</summary>
         /// <typeparam name="T">The type of asset to load.</typeparam>
@@ -145,6 +148,8 @@ namespace StardewModdingAPI.Framework
         /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
         /// <param name="instance">The content manager instance for which to load the asset.</param>
         public T LoadFor<T>(string assetName, ContentManager instance)
+        {
+            lock (this.Cache)
             {
                 assetName = this.NormaliseAssetName(assetName);
 
@@ -179,17 +184,21 @@ namespace StardewModdingAPI.Framework
                 this.TrackAssetLoader(assetName, instance);
                 return data;
             }
+        }
 
         /// <summary>Inject an asset into the cache.</summary>
         /// <typeparam name="T">The type of asset to inject.</typeparam>
         /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
         /// <param name="value">The asset value.</param>
         public void Inject<T>(string assetName, T value)
+        {
+            lock (this.Cache)
             {
                 assetName = this.NormaliseAssetName(assetName);
                 this.Cache[assetName] = value;
                 this.TrackAssetLoader(assetName, this);
             }
+        }
 
         /// <summary>Get the current content locale.</summary>
         public string GetLocale()
@@ -199,6 +208,8 @@ namespace StardewModdingAPI.Framework
 
         /// <summary>Get the cached asset keys.</summary>
         public IEnumerable<string> GetAssetKeys()
+        {
+            lock (this.Cache)
             {
                 IEnumerable<string> GetAllAssetKeys()
                 {
@@ -211,6 +222,7 @@ namespace StardewModdingAPI.Framework
 
                 return GetAllAssetKeys().Distinct();
             }
+        }
 
         /// <summary>Purge assets from the cache that match one of the interceptors.</summary>
         /// <param name="editors">The asset editors for which to purge matching assets.</param>
@@ -247,6 +259,8 @@ namespace StardewModdingAPI.Framework
         /// <param name="dispose">Whether to dispose invalidated assets. This should only be <c>true</c> when they're being invalidated as part of a dispose, to avoid crashing the game.</param>
         /// <returns>Returns whether any cache entries were invalidated.</returns>
         public bool InvalidateCache(Func<string, Type, bool> predicate, bool dispose = false)
+        {
+            lock (this.Cache)
             {
                 // find matching asset keys
                 HashSet<string> purgeCacheKeys = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
@@ -288,6 +302,7 @@ namespace StardewModdingAPI.Framework
                 this.Monitor.Log("Invalidated 0 cache entries.", LogLevel.Trace);
                 return false;
             }
+        }
 
         /// <summary>Dispose assets for the given content manager shim.</summary>
         /// <param name="shim">The content manager whose assets to dispose.</param>