Argument of type 'Dictionary<string, Title?>' cannot be used for parameter 'heritageToEmpireDict' of type 'Dictionary<string, Title>' in 'void LandedTitles.SplitDisconnectedEmpires(FrozenDictionary<string, ConcurrentHashSet<string>> kingdomAdjacenciesByLand, FrozenDictionary<string, ConcurrentHashSet<string>> kingdomAdjacenciesByWaterBody, HashSet<string> removableEmpireIds, Dictionary<string, ImmutableArray<Pillar>> kingdomToDominantHeritagesDict, Dictionary<string, Title> heritageToEmpireDict, CK3LocDB ck3LocDB, Date date)' due to differences in the nullability of reference types.