There's a very easy fix, outlined here. The issue is that GNURadio is asking wxGUI for the window size before the window is created. The fix is to edit top_block_gui.py. This file is likely located in ./usr/lib/python2.7/dist-packages/grc_gnuradio/wxgui/top_block_gui.py assuming your build prefix is /usr.
This defers creation of the GUI element and removes the error. And as you'd expect the autcorrelation of random noise is not very interesting :)