CHIRP

If a row is empty, the two "delete and shift" functions do not work.

Actual behavior:
Nothing happens to the blank row, and nothing is shifted. Further, there is the following traceback when attempting to do this. I'm sure this error occurs because there is nothing in the cells.

Traceback (most recent call last):
File "/usr/local/lib/python3.11/site-packages/chirp-next_20230112-py3.11.egg/chirp/wxui/memedit.py", line 900, in _delete_memories_at
LOG.debug('Moving memory %i -> %i', number, number - delta)
~~~~~^~~~~
TypeError: unsupported operand type(s) for -: 'str' and 'int'

Expected behavior:
The blank row would be removed and the rows beneath shifted up