Jquery Ajax prevent fail in a deferred sequential loop

Try

(function ($) {
    $.when.all = whenAll;
    function whenAll(arr) {
        "use strict";
        var deferred = new $.Deferred(),
            args = !! arr 
                   ? $.isArray(arr) 
                     ? arr 
                     : Array.prototype.slice.call(arguments)
                       .map(function (p) {
                         return p.hasOwnProperty("promise") 
                         ? p 
                         : new $.Deferred()
                           .resolve(p, null, deferred.promise())
                       }) 
                   : [deferred.resolve(deferred.promise())],
            promises = {
                "success": [],
                  "error": []
            }, doneCallback = function (res) {
                promises[this.state() === "resolved" 
                         || res.textStatus === "success" 
                         ? "success" 
                         : "error"].push(res);
                return (promises.success.length 
                       + promises.error.length) === args.length 
                       ? deferred.resolve(promises) 
                       : res
            }, failCallback = function (res) {
                // do `error` notification , processing stuff
                // console.log(res.textStatus);
                promises[this.state() === "rejected" 
                        || res.textStatus === "error" 
                        ? "error" 
                        : "success"].push(res);
                return (promises.success.length 
                       + promises.error.length) === args.length 
                       ? deferred.resolve(promises) 
                       : res
            };
        $.map(args, function (promise, index) {
            return $.when(promise).always(function (data, textStatus, jqxhr) {
                return (textStatus === "success") 
                    ? doneCallback.call(jqxhr, {
                        data: data,
                        textStatus: textStatus 
                                    ? textStatus 
                                    : jqxhr.state() === "resolved" 
                                      ? "success" 
                                      : "error",
                        jqxhr: jqxhr
                      }) 
                    : failCallback.call(data, {
                        data: data,
                        textStatus: textStatus,
                        jqxhr: jqxhr
                      })
            })
        });
        return deferred.promise()
    };
}(jQuery));
// returns `Object {
//                   success: Array[/* success responses*/], 
//                   error: Array[/* error responses */]
//          }`

---

// e.g.,
var request = function (url, data) {
    return $.post(url, {
        json: JSON.stringify(data)
    })
}, settings = [
    ["/echo/json/", "success1"], // `success`
    ["/echo/jsons/", "error1"], // `error`
    ["/echo/json/", "success2"], // `success`
    ["/echo/jsons/", "error2"], // `error`
    ["/echo/json/", "success3"] // `success`
];

$.when.all(
  $.map(settings, function (p) {
    return request.apply($, p)
  })
)
.then(function (data) {
    console.log(data);
    // filter , process responses
    $.each(data, function(key, value) {
        if (key === "success") {
          results.append(
              "\r\n" + key + ":\r\n" + JSON.stringify(value, null, 4)
          )
        } else {            
          results.append(
              "\r\n" + key + ":\r\n" 
              + JSON.stringify(
                  value.map(function(v, k) {
                    v.data.responseText = $(v.data.responseText)
                      .filter("title, #summary, #explanation")
                      .text().replace(/\s+/g, " ");
                    return v
                  })
                , null, 4)
          )
        }
    })
}, function (e) {
    console.log("error", e)
});

jsfiddle http://jsfiddle.net/guest271314/620p8q8h/