Table class does not like uneven columns

[pfuntner]

I found a bug when the Table class of table.py when you try to add a row with less columns than the number of headings:

$ cat ~/python/tabletest
#! /usr/bin/env python3

import logging
import argparse

from table import Table

parser = argparse.ArgumentParser(description='investigate table bug')
parser.add_argument('--boom', action='store_true', help='Cause exception')
parser.add_argument('-v', '--verbose', action='count', help='Enable debugging')
args = parser.parse_args()

logging.basicConfig(format='%(asctime)s %(levelname)s %(pathname)s:%(lineno)d %(msg)s')
log = logging.getLogger()
# log.setLevel(logging.DEBUG if args.verbose else logging.WARNING)
log.setLevel(logging.WARNING - (args.verbose or 0)*10)

table = Table('col1', 'col2')
table.add('row1, col1', 'row1, col2')
if args.boom:
  table.add('row2, col1')
print(str(table))
$ ~/python/tabletest
col1        col2
row1, col1  row1, col2

$ ~/python/tabletest  --boom
Traceback (most recent call last):
  File "/home/jpfuntne/python/tabletest", line 21, in <module>
    table.add('row2, col1')
  File "/home/jpfuntne/repos/fun/table.py", line 719, in add
    self.root.append({name: str(row[pos]) for (pos, name) in enumerate(self.headings)})
  File "/home/jpfuntne/repos/fun/table.py", line 719, in <dictcomp>
    self.root.append({name: str(row[pos]) for (pos, name) in enumerate(self.headings)})
IndexError: tuple index out of range
$

I don't know if this happens when you try to add a row that has more columns.

I'm not saying the class needs to pad or truncate columns when a row doesn't match the headings but the class should handle the situation better and make it clear that the number of columns is not correct.