I can reproduce the problem at 2.7.13 on Linux.


Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1542, in __call__
    return self.func(*args)
  File "tests.py", line 174, in get_style
    lb_sty_get =  listbox_style.get(lb_sty_cur)
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2629, in get
    return self.tk.call(self._w, 'get', first)
TclError: bad listbox index "": must be active, anchor, end, @x,y, or a number