The yafaray exporter crashes when clicking on the materials tab, if there are no materials in the scene.

The console error:

Traceback (most recent call last):
  File "/home/wizofboz/.blender/scripts/yafaray/yafaray_ui.py", line 2749, in gui
    TabMaterial.draw(height)
  File "/home/wizofboz/.blender/scripts/yafaray/yafaray_ui.py", line 468, in draw
    if self.blenderMat.lib:
AttributeError: 'NoneType' object has no attribute 'lib'