keep old XNB file extension behavior for backwards compatibility (#766)

src/SMAPI.sln.DotSettings

@@ -53,6 +53,7 @@
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Pathoschild/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=premultiplied/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=premultiply/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Prenormalize/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=prerelease/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=pufferchick/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=rewriter/@EntryIndexedValue">True</s:Boolean>

src/SMAPI/Framework/ContentManagers/BaseContentManager.cs

@@ -104,20 +104,21 @@ namespace StardewModdingAPI.Framework.ContentManagers
 
         /// <inheritdoc />
         [Obsolete("This method is implemented for the base game and should not be used directly. To load an asset from the underlying content manager directly, use " + nameof(BaseContentManager.RawLoad) + " instead.")]
-        public override T LoadBase<T>(string assetName)
+        public sealed override T LoadBase<T>(string assetName)
         {
             return this.Load<T>(assetName, LanguageCode.en);
         }
 
         /// <inheritdoc />
-        public override T Load<T>(string assetName)
+        public sealed override T Load<T>(string assetName)
         {
             return this.Load<T>(assetName, this.Language);
         }
 
         /// <inheritdoc />
-        public override T Load<T>(string assetName, LanguageCode language)
+        public sealed override T Load<T>(string assetName, LanguageCode language)
         {
+            assetName = this.PrenormalizeRawAssetName(assetName);
             IAssetName parsedName = this.Coordinator.ParseAssetName(assetName);
             return this.LoadLocalized<T>(parsedName, language, useCache: true);
         }
@@ -276,6 +277,21 @@ namespace StardewModdingAPI.Framework.ContentManagers
         /*********
         ** Private methods
         *********/
+        /// <summary>Apply initial normalization to a raw asset name before it's parsed.</summary>
+        /// <param name="assetName">The asset name to normalize.</param>
+        private string PrenormalizeRawAssetName(string assetName)
+        {
+            // trim
+            assetName = assetName?.Trim();
+
+            // For legacy reasons, mods can pass .xnb file extensions to the content pipeline which
+            // are then stripped. This will be re-added as needed when reading from raw files.
+            if (assetName?.EndsWith(".xnb") == true)
+                assetName = assetName[..^".xnb".Length];
+
+            return assetName;
+        }
+
         /// <summary>Normalize path separators in a file path. For asset keys, see <see cref="AssertAndNormalizeAssetName"/> instead.</summary>
         /// <param name="path">The file path to normalize.</param>
         [Pure]

src/SMAPI/Framework/ContentManagers/ModContentManager.cs

@@ -32,9 +32,6 @@ namespace StardewModdingAPI.Framework.ContentManagers
         /// <summary>The game content manager used for map tilesheets not provided by the mod.</summary>
         private readonly IContentManager GameContentManager;
 
-        /// <summary>The language code for language-agnostic mod assets.</summary>
-        private readonly LanguageCode DefaultLanguage = Constants.DefaultLanguage;
-
         /// <summary>If a map tilesheet's image source has no file extensions, the file extensions to check for in the local mod folder.</summary>
         private readonly string[] LocalTilesheetExtensions = { ".png", ".xnb" };
 
@@ -75,12 +72,6 @@ namespace StardewModdingAPI.Framework.ContentManagers
             return file.Exists;
         }
 
-        /// <inheritdoc />
-        public override T Load<T>(string assetName)
-        {
-            return this.Load<T>(assetName, this.DefaultLanguage);
-        }
-
         /// <inheritdoc />
         public override T LoadExact<T>(IAssetName assetName, bool useCache)
         {
@@ -222,14 +213,14 @@ namespace StardewModdingAPI.Framework.ContentManagers
         private FileInfo GetModFile(string path)
         {
             // try exact match
-            FileInfo file = new FileInfo(Path.Combine(this.FullRootDirectory, path));
+            FileInfo file = new(Path.Combine(this.FullRootDirectory, path));
 
             // try with default extension
-            if (!file.Exists && file.Extension == string.Empty)
+            if (!file.Exists)
             {
                 foreach (string extension in this.LocalTilesheetExtensions)
                 {
-                    FileInfo result = new FileInfo(file.FullName + extension);
+                    FileInfo result = new(file.FullName + extension);
                     if (result.Exists)
                     {
                         file = result;

src/SMAPI/Metadata/CoreAssetPropagator.cs

@@ -95,8 +95,6 @@ namespace StardewModdingAPI.Metadata
                 .Distinct()
                 .ToDictionary(name => name, _ => false);
 
-            this.Monitor.Log($"Propagating: {propagatedAssets.Keys.OrderBy(p => p.Name, StringComparer.OrdinalIgnoreCase)}", LogLevel.Alert);
-
             // group into optimized lists
             var buckets = assets.GroupBy(p =>
             {