Provides a custom string representation of the error object. This is an override of the base JavaScript
`Object.toString` method, which is useful so that when logged to the browser console, an error object will
be displayed with a useful message instead of `[object Object]`, the default `toString` result.

The default implementation will include the error message along with the raising class and method, if available,
but this can be overridden with a custom implementation either at the prototype level (for all errors) or on
a particular error instance, if you want to provide a custom description that will show up in the console.
@return {String} The error message. If raised from within the Ext 4 class system, the error message will also
include the raising class and method names, if available.
function(){
        var me = this,
            className = me.sourceClass ? me.sourceClass : '',
            methodName = me.sourceMethod ? '.' + me.sourceMethod + '(): ' : '',
            msg = me.msg || '(No description provided)';

        return className + methodName + msg;
    }