Multiple items inside Media tagmap variables makes it broken.

Hi Guys!

I was having a really bad experience with Media module, specifically with media.filter.js. I have multiple WYSIWYG editors (CKEditor in my case) on the form with ability to add more. I don't think this is a case, but WYSIWYGs were inside nested Field Collections. Anyway, when I add new WYSIWYG item to the form with the help of AJAX, it results with this nice JS error (in chrome): Uncaught NotFoundError: An attempt was made to reference a Node in a context where it does not exist.

I'm using:
Media 7.x-2.x
WYSYWYG 7.x-2.x
CKEditor 4.1.0

Because Drupal extends Drupal.settings object on every AJAX response media tags inside Drupal.settings.tagmap become arrays instead of string. This was resulting error inside Drupal.media.filter.create_element. I've made a small workaround for Drupal.media.filter.ensure_tagmap to ensure that media tags inside will always be string (no array).

Also, I had another issue, when after some AJAX requests tagmap was empty. I had not time to debug this issue and made a workaround with a local tagmap (tagmap backup), which I assign to Drupal.settings.tagmap in case it is empty. Probably this issue happens because Field Collection, very hard to say. Anyway, workaround works.

I'm posting a patch here (in comments). I do not think this patch will get into the media dev version. I hope guys that develop media module will get around with this issue in more elegant way.
For those, who do not like to hack module, you may insert this code inside your custom JS:

(function($) {
    $(document).ready(function() {
        if(Drupal.media && Drupal.media.filter) {
            tagmap_local = {};
            $.extend(Drupal.media.filter, {
                ensure_tagmap: function() {
                    Drupal.settings.tagmap = Drupal.settings.tagmap || {};

                    if ($.isEmptyObject(Drupal.settings.tagmap) && !$.isEmptyObject(tagmap_local)) {
                        Drupal.settings.tagmap = tagmap_local;
                    }

                    tagmap_local = Drupal.settings.tagmap;

                    for (var i in Drupal.settings.tagmap) {
                        if (!Drupal.settings.tagmap[i]) {
                            continue;
                        }
                        Drupal.settings.tagmap[i] = Object.prototype.toString.call(Drupal.settings.tagmap[i]) === "[object Array]" ? Drupal.settings.tagmap[i].shift() : Drupal.settings.tagmap[i];
                    }

                    return Drupal.settings.tagmap;
                }
            });            
        }
    });
})(jQuery);