[v1.7.1] TypeError - d:\OpenNumismat\open-numismat\OpenNumismat\Reference\ReferenceDialog.py:251

OpenNumismat: 1.7.1
OS: Windows 7 (6.1.7601)
Python: 3.4.4 (32bit)
Qt: 5.5.1
Locale: fr

Traceback (most recent call last):
File "d:\OpenNumismat\open-numismat\OpenNumismat\Reference\Reference.py", line 106, in clickedButton
File "d:\OpenNumismat\open-numismat\OpenNumismat\Reference\Reference.py", line 258, in _getDialog
File "d:\OpenNumismat\open-numismat\OpenNumismat\Reference\ReferenceDialog.py", line 345, in __init__
File "d:\OpenNumismat\open-numismat\OpenNumismat\Reference\ReferenceDialog.py", line 299, in __init__
File "d:\OpenNumismat\open-numismat\OpenNumismat\Reference\ReferenceDialog.py", line 348, in _referenceWidget
File "d:\OpenNumismat\open-numismat\OpenNumismat\Reference\ReferenceDialog.py", line 242, in __init__
File "d:\OpenNumismat\open-numismat\OpenNumismat\Reference\ReferenceDialog.py", line 251, in currentIndexChanged
TypeError: %d format: a number is required, not NoneType