Add a clarifying comment, and remove unnecessary assignment. I don't honestly recall if this was even intentionally included or a copy-paste error, but it does seem like knowing your image is busted at compile time is much better than not knowing til runtime.

git-svn-id: svn+ssh://src.earth.threerings.net/nenya/trunk@594 ed5b42cb-e716-0410-a449-f6a68f950b19

src/java/com/threerings/media/tile/bundle/tools/DirectoryTileSetBundler.java

@@ -128,7 +128,9 @@ public class DirectoryTileSetBundler extends TileSetBundler
                     }
 
                     try {
-                        BufferedImage image = ImageIO.read(ifile);
+                        // We read the image to ensure it is a valid image.
+                        ImageIO.read(ifile);
+
                         File outFile = new File(target, imagePath);
                         if (outFile.lastModified() > newestMod) {
                             // Our file's newer than the newest bundle mod - up to date.