UberMenu initialized via window.load
This is not an error. It is a notice alerting you that UberMenu was loaded on the window load event rather than the document ready event.
This means that UberMenu is using a fallback event because something has prevented it from loading during the normal event.
As a fallback, UberMenu will also try to load on the window load event, in case the document ready event failed to run. In this case, this message will print so that you will be aware of the issue. This allows UberMenu to run even though you have an issue with some other code on your site.