prevent Steam vdf read errors from crashing the installer

docs/release-notes.md

@@ -8,6 +8,9 @@
 -->
 
 ## Upcoming release
+* For players:
+  * Fixed installer crash if Steam's library data is invalid or in an old format; it'll now be ignored instead.
+
 * For mod authors:
   * Fixed image patches sometimes applied one pixel higher than expected after 3.17.0 (thanks to atravita!).
 

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

@@ -260,6 +260,8 @@ namespace StardewModdingAPI.Toolkit.Framework.GameScanning
         /// <param name="steamPath">The full path to the directory containing steam.exe.</param>
         /// <returns>The game directory, if found.</returns>
         private string? GetPathFromSteamLibrary(string? steamPath)
+        {
+            try
             {
                 if (steamPath == null)
                     return null;
@@ -295,6 +297,15 @@ namespace StardewModdingAPI.Toolkit.Framework.GameScanning
 
                 return null;
             }
+            catch
+            {
+                // The file might not be parseable in some cases (e.g. some players have an older Steam version using
+                // a different format). Ideally we'd log an error to know when it's actually an issue, but the SMAPI
+                // installer doesn't have a logging mechanism (and third-party code calling the toolkit may not either).
+                // So for now, just ignore the error and fallback to the other discovery mechanisms.
+                return null;
+            }
+        }
 #endif
     }
 }