Fix ambiguous warning messages

[LouisdeBruijn]

Fixes ambiguous warning messages for table_checkpoint and checkpoint_dir Adds ValueError when both col_names and field_info are given

def if_else(a, b):
	""""""
	if not a and b:
		pass
	else:
		print(f"warning. a: {a}, b: {b}.")

a, b = True, True
if_else(a, b)
a, b = False, True
if_else(a, b)
a, b = True, False
if_else(a, b)
a, b = False, False
if_else(a, b)

$ warning. a: True, b: True.
$ warning. a: True, b: False.
$ warning. a: False, b: False.