fix install error if a game folder has an invalid symlink

docs/release-notes.md

@@ -11,6 +11,7 @@
 * For players:
   * In multiplayer, the game/SMAPI window titles now show whether you're the main player or a farmhand.
   * Fixed logged SMAPI errors not having line numbers on Linux/macOS.
+  * Fixed install error if a game folder has an invalid symlink.
 
 * For mod authors:
   * Fixed error loading a mod if it sets `"MinimumApiVersion": null` explicitly.

src/SMAPI.Toolkit/Framework/GameScanning/GameScanner.cs

@@ -73,7 +73,7 @@ namespace StardewModdingAPI.Toolkit.Framework.GameScanning
                 return GameFolderType.NoGameFound;
 
             // apparently valid
-            if (dir.EnumerateFiles("Stardew Valley.dll").Any())
+            if (File.Exists(Path.Combine(dir.FullName, "Stardew Valley.dll")))
                 return GameFolderType.Valid;
 
             // doesn't contain any version of Stardew Valley