Google maps data type throws Type Error: can't convert undefined to object
===

In all our Umbraco websites Google maps data type is not working anymore. This worked perfect till yesterday but today there is only the input-field and the location-field and not the Google maps... 

Firebug reports the following error

Error: TypeError: can't convert undefined to object
Source File: http://mydomain.com/WebResource.axd?d=tKK1ZgJBCMotVXJtV8pR9xzMqTmklCMezxGDl1po1iuUqd9OAFswOEzHFzCaf_jVz-AUweHtY9QXIBqtRjeITKZJW8DsgNEfWr5d43rOLcGkPLOTDqcjla1Kf5Atxrk4V0fVru8i1i6pj_kgbZvebWAyHrkbCDipPWDziYWT-lCHW-WaHOcz5hS1DefZvkJSICxqjpdChghoCUZhju3cHg2&amp;t=634759042640000000&cdv=1
Line: 212

Its in the line  

    context._maps[id] = new UmbracoGoogleMap.map(id, this);

in the following function  

    guiMap: function () {
        var context = this;
        this._apiLoaded = true;
        jQuery('div.gmapContainer').each(function () {
            var id = jQuery('div.map', this).attr('id');
            context._maps[id] = new UmbracoGoogleMap.map(id, this);
            context._maps[id].render();
        });
    },

There is a lot of other people also reporting the same issue but couldn't find a solution yet!
http://our.umbraco.org/projects/backoffice-extensions/google-maps-datatype/bug-reports/33390-No-map-in-Backend