code: @Override
  	public void onError(InvocationContext context, Exception error) {
  		
  		AsyncHandler<Object> asyncHandler = getAsyncHandler(context);
  		
  		if(asyncHandler != null) {
  			
  			try {
  			
  				asyncHandler.onError(error instanceof InvocationException? 
  						(InvocationException)error :InvocationException.newInstance(context, error));
  				}
  			catch(Exception e) {
  				
  				Log.e(getClass().getSimpleName(), "Callback \"onError\" aborted with an exception.", e);
  			}
  		}
  	}
docs: <p>If an {@link AsyncHandler} is defined, any exception which resulted in an error will be
  available via the <i>onError</i> callback.</p>
  
  <p>See {@link ExecutionHandler#onError(InvocationContext, Exception)}</p>
  
  @param context
  the {@link InvocationContext} with information on the proxy invocation
  <br><br>
  @param error
  the exception which resulted in a request execution failure
  <br><br>
  @since 1.3.0