Validate responses client side

[GentlemanHal]

We had an issue at work which resulted in a e.filter is not a function error (the e is because we are using the minified production build).

After a little investigation it seems the issue was the web proxy. It decided to not allow the calls to the Nevergreen server and was returning a OK status but with a html webpage instead of json. So I suspect the code is just getting back a string instead of an array.

This is low priority as the only way something like this should ever happen is some kinda of proxy problem and if your proxy is broken then nothing is going to work anyways, but it would be nice to display a more informative and potentially helpful error message.