Newbie here

i have this method in my source adapter
this.query = function(resp) {
new rc.ServerErrorException(resp, "Server not available.Contact your administrator");
        var result = {};
        var str = '';
      resp.send(result);

I am able to catch the error message on my ui using
params["server_errors"]["create-error"][object]["message"];

If i do the same in the create or update method of source adapter i am not able to catch the error ,i tried methods from docs it still wouldn't work , if anybody can provide the proper javascript syntax that would be much appreciated.