Percentiles is a feature we're planning on adding at some point in the future, though we have customers calculating it themselves right now using things like metriks-instrumental ( https://github.com/netshade/metriks-instrumental ).

Alerts is actually in beta right now :) - we're testing it out with a few customers. It's based on our query language, and alerts you with a graph of the problem when the event occurs. ( or updates an HTTP endpoint you control, if you wish )

edit: I forgot to mention, my apologies you encountered an error. We've been living on the edge of browser support land for the time being, and could do a better job letting you know that you're not meeting the minimum reqs.