[2.??] json.js incompatability

[1900]

Within a portal environment which uses function from a library json.js against javascript Arrays, extJS is throwing an exception during the destroy of grid panels.

The library json.js contains a prototype for 'Object'. This adds a toJSONString function via 'Object.prototype.toJSONString'.

The destroy function is not checking the 'dds[dd]' that it either has a 'config' object or is an object itself.

Suggesting to check the var somehow... ie:

if (!dds[dd].config) {
} else
if(!dds[dd].config.isTarget && dds[dd].dragElId){

This occurs through and including v2.1.

in V2.1
line 30729 throws exception when

        if(this.grid.enableColumnMove){
            var dds = Ext.dd.DDM.ids['gridHeader' + this.grid.getGridEl().id];
            if(dds){
                for(var dd in dds){
                    if(!dds[dd].config.isTarget && dds[dd].dragElId){
                        var elid = dds[dd].dragElId;
                        dds[dd].unreg();
                        Ext.get(elid).remove();