Handle missing cultures when setting de jure empires (#1501) #patch

ImperatorToCK3/CK3/Provinces/ProvinceHistory.cs

@@ -1,5 +1,6 @@
 using commonItems;
 using commonItems.Collections;
+using ImperatorToCK3.CK3.Cultures;
 using ImperatorToCK3.CommonUtils;
 using System.Collections.Generic;
 using System.Collections.Immutable;
@@ -31,6 +32,18 @@ public void SetFaithId(string faithId, Date? date) {
 	public void SetCultureId(string cultureId, Date? date) {
 		History.AddFieldValue(date, "culture", "culture", cultureId);
 	}
+
+	public Culture? GetCulture(Date date, CultureCollection cultures) {
+		var cultureId = GetCultureId(date);
+		if (cultureId is null) {
+			return null;
+		}
+		if (cultures.TryGetValue(cultureId, out var culture)) {
+			return culture;
+		}
+		Logger.Warn($"Culture with ID {cultureId} not found!");
+		return null;
+	}
 
 	public string? GetHoldingType(Date date) {
 		var historyValue = History.GetFieldValue("holding", date);

ImperatorToCK3/CK3/Titles/LandedTitles.cs

@@ -641,9 +641,8 @@ public void SetDeJureKingdomsAndEmpires(Date ck3BookmarkDate, ProvinceCollection
 				var kingdomProvinceIds = counties.SelectMany(c => c.CountyProvinces).ToImmutableHashSet();
 				var kingdomProvinces = ck3Provinces.Where(p => kingdomProvinceIds.Contains(p.Id));
 				var dominantHeritage = kingdomProvinces
-					.Select(c => new { County = c, CultureId = c.GetCultureId(ck3BookmarkDate)})
-					.Where(x => x.CultureId is not null)
-					.Select(x => new { x.County, ck3Cultures[x.CultureId!].Heritage })
+					.Select(p => new { Province = p, p.GetCulture(ck3BookmarkDate, ck3Cultures)?.Heritage})
+					.Where(x => x.Heritage is not null)
 					.GroupBy(x => x.Heritage)
 					.MaxBy(g => g.Count())?.Key;
 				if (dominantHeritage is null) {