improve the error handling

war/src/main/webapp/scripts/hudson-behavior.js

@@ -1970,6 +1970,11 @@ var downloadService = {
             id = data.id;
         }
         var o = this.continuations[id];
+        if (o==undefined) {
+            console.log("Submission from update center that we don't know: "+id);
+            console.log("Likely mismatch between the registered ID vs ID in JSON");
+            return;
+        }
         // send the payload back in the body. We used to send this in as a form submission, but that hits the form size check in Jetty.
         new Ajax.Request(o.postBack, {
             contentType:"application/json",