Not so much a bug, as it doesn't affect gameplay, but it does throw an error in the Modding log and has been present since Catherine's persona release.
In the Catherine de Medici modinfo there is a file listed as "CatherineDeMedici_Modifiers.xml". This file doesn't exist and the modifiers are actually in the CatherineDeMedici_Leaders.xml file.
If you're kind of particular about having clean, error free logs like me then the two entries with the missing file can safely be deleted to eliminate the error.
In the Catherine de Medici modinfo there is a file listed as "CatherineDeMedici_Modifiers.xml". This file doesn't exist and the modifiers are actually in the CatherineDeMedici_Leaders.xml file.
If you're kind of particular about having clean, error free logs like me then the two entries with the missing file can safely be deleted to eliminate the error.
