Error on clipboard_appkit

gistfile1.txt

 Traceback (most recent call last):
   File "main.py", line 169, in <module>
     Controller().run()
   File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/kivy/app.py", line 728, in run
     runTouchApp()
   File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/kivy/base.py", line 469, in runTouchApp
     EventLoop.window.mainloop()
   File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/kivy/core/window/window_pygame.py", line 335, in mainloop
     self._mainloop()
   File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/kivy/core/window/window_pygame.py", line 302, in _mainloop
     self.modifiers):
   File "_event.pyx", line 310, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:4352)
   File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/kivy/core/window/__init__.py", line 131, in _on_window_key_down
     return self.dispatch('on_key_down', keycode, text, modifiers)
   File "_event.pyx", line 310, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:4352)
   File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/kivy/uix/textinput.py", line 1643, in _keyboard_on_key_down
     self._copy(self.selection_text)
   File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/kivy/uix/textinput.py", line 1065, in _copy
     Clipboard.put(data, self._clip_mime_type)
 AttributeError: 'NoneType' object has no attribute 'put'