Address nullable default value

CHANGELIST.md

@@ -18,6 +18,7 @@
 - IsAudio cleanup cleanup
 - Remove dead code in DIC processor
 - Set some default values for CLI
+- Address nullable default value
 
 ### 3.3.2 (2025-06-12)
 

MPF.CLI/Program.cs

@@ -237,7 +237,7 @@ namespace MPF.CLI
             // Create return values
             var opts = new CommandOptions
             {
-                FilePath = Path.Combine(options.DefaultOutputPath, "track.bin"),
+                FilePath = Path.Combine(options.DefaultOutputPath ?? "ISO", "track.bin"),
             };
             mediaType = MediaType.NONE;
             system = options.DefaultSystem;