openlayers wms loaderror event get response text of

Question

1.How do I get the http response text & error code from OpenLayers 2.12 WMS loaderror event ?

2.The WMS request returns returns http error code 500 with some response text, however, as per image below, I can't get those details.

3.Workaround: I send a HEAD request in the 'loaderror' handler

                    intramapsConfig = {
                        name : "MapImage WMS",
                        options : { "ratio": 1, "singleTile": true,
                                    "removeBackBufferDelay": 500 ,
                                    "transitionEffect" : "resize",
                                    "tileOptions": {
                                    "eventListeners": {
                                            'loaderror': function(evt) {
                                                console.log('loaderror');
                                                debugger;
                                                $.ajax({
                                                    type: "HEAD",
                                                    async: false,
                                                    url: evt.object.url,
                                                    success: function(message,text,response){
                                                        debugger;
                                                    },
                                                    error: function(error) {
                                                        debugger;
                                                    }
                                                });

                                            }
                                        }
                                }
                        }

4.The image below is the event object sent by onImageError function.