Add error message for when ZIP fails

extensions/cck/browser/locales/en-US/chrome/cckwizard.properties

@@ -2,4 +2,4 @@ windowTitle=Firefox CCK
 deleteConfirm=Are you sure you want to delete this configuration?
 outputLocation=Firefox CCK Wizard is completed. XPI is available at:\n
 cancelConfirm=Do you want to save your changes?
-
+zipError=Unable to create JAR or XPI file. Please ensure that a command line version of ZIP is in your path or that you have specified a path to ZIP.

extensions/cck/browser/resources/content/cckwizard/cckwizard.js

@@ -859,7 +859,14 @@ function CCKZip(zipfile, location)
   var args = [file.path];
   
   process.run(true, args, args.length);
-//  file.remove(false);
+  file.remove(false);
+  var file = location.clone();
+  file.append(zipfile);
+  if (!file.exists()) {
+    var bundle = document.getElementById("bundle_cckwizard");
+    gPromptService.alert(window, bundle.getString("windowTitle"),
+                       bundle.getString("zipError"));
+  }
 }
 
 function CCKWriteXULOverlay(destdir)