Fix if file was not readed

uglifyjs-fix-fileread.patch

diff --git a/bin/uglifyjs b/bin/uglifyjs
index ad3866f..02f0268 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -105,7 +105,11 @@ out: while (args.length > 0) {

 if (filename) {
         fs.readFile(filename, "utf8", function(err, text){
-                output(squeeze_it(text));
+                if(err) {
+                   sys.debug(err);
+               } else {
+                   output(squeeze_it(text));
+               }
         });
 } else {
         var stdin = process.openStdin();