Probably a nice touch to set a default.

Not that NPEing when you don't go out of
your way to use the new stuff isn't fun...

tools/src/main/java/com/threerings/media/tile/bundle/tools/TileSetBundler.java

@@ -205,7 +205,11 @@ public class TileSetBundler
 
         boolean trim = true;
         boolean raw = true;
-        Supplier<TileSetTrimmer.Packer> packer;
+        Supplier<TileSetTrimmer.Packer> packer = new Supplier<TileSetTrimmer.Packer>() {
+            public TileSetTrimmer.Packer get () {
+                return new TileSetTrimmer.StripPacker();
+            }
+        };
         String imageBase;
         JSONConversion.Config json;
     }