An event that is raised when a request encounters an error.
    
| Name | Type | Description | 
|---|---|---|
statusCode | 
            
            Number | optional The HTTP error status code, such as 404. | 
response | 
            
            Object | optional The response included along with the error. | 
responseHeaders | 
            
            String | Object | optional The response headers, represented either as an object literal or as a string in the format returned by XMLHttpRequest's getAllResponseHeaders() function. | 
Members
    The response included along with the error.  If the error does not include a response,
this property will be undefined.
    The headers included in the response, represented as an object literal of key/value pairs.
If the error does not include any headers, this property will be undefined.
    The HTTP error status code, such as 404.  If the error does not have a particular
HTTP code, this property will be undefined.
Methods
    Creates a string representing this RequestErrorEvent.
Returns:
    A string representing the provided RequestErrorEvent.
    
