Is there anyway I can handle both json and html return types when posting jquery ajax:

For example, this ajax call expects html back

$.ajax({
            type: "POST",
            url: url
            data: data,
            dataType: "html",
            success: function (response) {
                var $html = "<li class='list-item'>" + response + "</li>";
                $('#a').prepend($html);                           
            },
            error: function (xhr, status, error) {
                alert(xhr.statusText);
            }
        });

but I wanted to modify it so that I can return a json object if there is a model error. so I can do something like this:

success: function (response) {
          if (response.Error){
                 alert(response.Message);   
          } else {
              var $html = "<li class='list-item'>" + response + "</li>";
              $('#a').prepend($html);                           
          }

Is this possible?