[v1.8.11] TypeError - OpenNumismat\Reports\Report.py:126

OpenNumismat: 1.8.11
OS: Windows 10 (10.0.19041)
Python: 3.4.4 (32bit)
Qt: 5.5.1
Locale: en

Traceback (most recent call last):
File "OpenNumismat\MainWindow.py", line 729, in viewBrowserEvent
File "OpenNumismat\ListView.py", line 209, in viewInBrowser
File "OpenNumismat\Reports\Report.py", line 126, in generate
TypeError: %d format: a number is required, not NoneType