traceback of kivy textinput crash

gistfile1.txt

  File "main.py", line 138, in <module>
    app.run()
  File "/usr/local/lib/python3.5/dist-packages/kivy/app.py", line 828, in run
    runTouchApp()
  File "/usr/local/lib/python3.5/dist-packages/kivy/base.py", line 504, in runTouchApp
    EventLoop.window.mainloop()
  File "/usr/local/lib/python3.5/dist-packages/kivy/core/window/window_sdl2.py", line 663, in mainloop
    self._mainloop()
  File "/usr/local/lib/python3.5/dist-packages/kivy/core/window/window_sdl2.py", line 602, in _mainloop
    self.modifiers):
  File "kivy/_event.pyx", line 714, in kivy._event.EventDispatcher.dispatch (/tmp/pip-errl7v17-build/kivy/_event.c:8146)
  File "kivy/_event.pyx", line 1225, in kivy._event.EventObservers.dispatch (/tmp/pip-errl7v17-build/kivy/_event.c:14035)
  File "kivy/_event.pyx", line 1149, in kivy._event.EventObservers._dispatch (/tmp/pip-errl7v17-build/kivy/_event.c:13564)
  File "/usr/local/lib/python3.5/dist-packages/kivy/core/window/__init__.py", line 159, in _on_window_key_down
    return self.dispatch('on_key_down', keycode, text, modifiers)
  File "kivy/_event.pyx", line 714, in kivy._event.EventDispatcher.dispatch (/tmp/pip-errl7v17-build/kivy/_event.c:8146)
  File "kivy/_event.pyx", line 1225, in kivy._event.EventObservers.dispatch (/tmp/pip-errl7v17-build/kivy/_event.c:14035)
  File "kivy/_event.pyx", line 1149, in kivy._event.EventObservers._dispatch (/tmp/pip-errl7v17-build/kivy/_event.c:13564)
  File "/usr/local/lib/python3.5/dist-packages/kivy/uix/textinput.py", line 2438, in keyboard_on_key_down
    self._key_down(key)
  File "/usr/local/lib/python3.5/dist-packages/kivy/uix/textinput.py", line 2298, in _key_down
    self.insert_text(u'\n')
  File "/usr/local/lib/python3.5/dist-packages/kivy/uix/textinput.py", line 713, in insert_text
    text = self._lines[cr]
IndexError: list index out of range