list, int and .grid() come on!

[buran]

Actually this code will give you

Error:
Traceback (most recent call last):
  File "***", line 8, in <module>
    piece_counter = piece_counter[piece_index].grid(row    = r,
IndexError: list index out of range

that is because piece_counter is empty list and there is no element at index 0.
please, post actual code you run as well as full traceback you get (not just the last line).

also note that start imports are generally discouraged
better
import tkinter as tk and then use the tk to fully reference whatever you used from imported module.