@tommck Where is your data comming from? If it is some remote source, then the server side is responsible for indexes handling and the front end should not care about this. If you are using ui-scroll datasource.get as a data generator, then negative indexes handling is a part of your datasource logic. Anyway this logic should be implemented somewhere out of ui-scroll directive cause ui-scroll directive is not responsible for data generation and there is no option to tell the ui-scroll that the data will have no negative indexes at all. There may be a lot of ways how to implement it, e.g. https://github.com/angular-ui/ui-scroll/blob/master/demo/chat/chat.js.
Regarding error handling... Still the ui-scroll directive is not responsible for the data generation and the ui-scroll datasource.get is the only place for data retrieving, then I guess datasource.get should be used also for errors handling. And again, there's total freedom: in the example I just mentioned it may looked like
Server.request(start, end).then(success).catch(errorHandler). So this falls to the ui-scroll user too.