For some reason when trying to update my slider on mytest wiki and adding an ploaded image to a page, I am getting an "Exception Caught: ExternalStoreDB::store: no insert ID" VisualEditor error and cannot seem to update the mainpage with the code changes I made. Explain this error please and perhaps help me work away around it. I am thinking perhaps since it uses the old image slider rather than the new one
Have you tried uploading the image using either the source editor or RTE to see if there's any difference? I generally find it's easier to make these sorts of things work in source editor. It would also be a good way to see if it's a problem with Wikia as a whole or just the VisualEditor.