Prevent 'save' when dataBinder not yet loaded
On slow systems there can be a delay between the form page displaying, and the form itself displaying. In these cases, if the 'save' method is called it is possible to save an empty dataBinder which could cause form data to be overwritten and lost. We will need to maintain a loaded status on the dataBinder and only allow a 'save' to be called when the data is loaded successfully.