After the board is filled in the Tic Tac Toe game, the program crashes with an error:

TypeError: list indices must be integers or slices, not NoneType
Cause:
The compMove() function returns None when no moves are left, but the program tries to insert at board[None].

Suggested Solution:
Before calling insertLetter("O", move), check if move is None and handle it as a tie.

Example:
if move == 0 or move is None:
print("Tie game")
else:
insertLetter("O", move)
print(f"Computer placed O on position {move}")
printBoard(board)

Additional Suggestion:
In compMove(), add a check:
if len(possibleMoves) == 0:
return None

Happy to work on fixing this if you would like! 🚀