[v1.8.8] KeyError - OpenNumismat\ListView.py:551

OpenNumismat: 1.8.8
OS: Windows 10 (10.0.18362)
Python: 3.4.4 (32bit)
Qt: 5.5.1
Locale: cs

Traceback (most recent call last):
File "OpenNumismat\ListView.py", line 551, in lessThan
KeyError: 'Missing'