Game can deal gracefully wth mods removing certain units and technologies

core/src/com/unciv/logic/GameInfo.kt

@@ -262,35 +262,7 @@ class GameInfo {
             throw UncivShowableException("Missing mods: [$missingMods]")
         }
 
-        // Mods can change, leading to things on the map that are no longer defined in the mod.
+        removeMissingModReferences()
-        // So we remove them so the game doesn't crash when it tries to access them.
-        for (tile in tileMap.values) {
-            if (tile.resource != null && !ruleSet.tileResources.containsKey(tile.resource!!))
-                tile.resource = null
-            if (tile.improvement != null && !ruleSet.tileImprovements.containsKey(tile.improvement!!)
-                    && !tile.improvement!!.startsWith("StartingLocation ")) // To not remove the starting locations in GameStarter.startNewGame()
-                tile.improvement = null
-
-            for (unit in tile.getUnits())
-                for (promotion in unit.promotions.promotions.toList())
-                    if (!ruleSet.unitPromotions.containsKey(promotion))
-                        unit.promotions.promotions.remove(promotion)
-
-            for (city in civilizations.asSequence().flatMap { it.cities.asSequence() }) {
-                for (building in city.cityConstructions.builtBuildings.toHashSet())
-                    if (!ruleSet.buildings.containsKey(building))
-                        city.cityConstructions.builtBuildings.remove(building)
-
-                // Remove invalid buildings or units from the queue - don't just check buildings and units because it might be a special construction as well
-                for (construction in city.cityConstructions.constructionQueue.toList()) {
-                    if (!ruleSet.buildings.containsKey(construction) && !ruleSet.units.containsKey(construction)
-                            && !PerpetualConstruction.perpetualConstructionsMap.containsKey(construction))
-                        city.cityConstructions.constructionQueue.remove(construction)
-                }
-            }
-
-
-        }
 
         tileMap.setTransients(ruleSet)
 
@@ -347,6 +319,46 @@ class GameInfo {
         }
     }
 
+
+    // Mods can change, leading to things on the map that are no longer defined in the mod.
+    // So we remove them so the game doesn't crash when it tries to access them.
+    private fun removeMissingModReferences() {
+        for (tile in tileMap.values) {
+            if (tile.resource != null && !ruleSet.tileResources.containsKey(tile.resource!!))
+                tile.resource = null
+            if (tile.improvement != null && !ruleSet.tileImprovements.containsKey(tile.improvement!!)
+                    && !tile.improvement!!.startsWith("StartingLocation ")) // To not remove the starting locations in GameStarter.startNewGame()
+                tile.improvement = null
+
+            for (unit in tile.getUnits()) {
+                if (!ruleSet.units.containsKey(unit.name)) tile.removeUnit(unit)
+
+                for (promotion in unit.promotions.promotions.toList())
+                    if (!ruleSet.unitPromotions.containsKey(promotion))
+                        unit.promotions.promotions.remove(promotion)
+            }
+
+        }
+
+        for (city in civilizations.asSequence().flatMap { it.cities.asSequence() }) {
+            for (building in city.cityConstructions.builtBuildings.toHashSet())
+                if (!ruleSet.buildings.containsKey(building))
+                    city.cityConstructions.builtBuildings.remove(building)
+
+            // Remove invalid buildings or units from the queue - don't just check buildings and units because it might be a special construction as well
+            for (construction in city.cityConstructions.constructionQueue.toList()) {
+                if (!ruleSet.buildings.containsKey(construction) && !ruleSet.units.containsKey(construction)
+                        && !PerpetualConstruction.perpetualConstructionsMap.containsKey(construction))
+                    city.cityConstructions.constructionQueue.remove(construction)
+            }
+        }
+        for (civinfo in civilizations) {
+            for (tech in civinfo.tech.techsResearched.toList())
+                if (!ruleSet.technologies.containsKey(tech))
+                    civinfo.tech.techsResearched.remove(tech)
+        }
+    }
+
     private fun changeBuildingName(cityConstructions: CityConstructions, oldBuildingName: String, newBuildingName: String) {
         if (cityConstructions.builtBuildings.contains(oldBuildingName)) {
             cityConstructions.builtBuildings.remove(oldBuildingName)

core/src/com/unciv/logic/civilization/TechManager.kt

@@ -18,6 +18,7 @@ import kotlin.math.min
 class TechManager {
     @Transient
     lateinit var civInfo: CivilizationInfo
+    /** This is the Transient list of Technologies */
     @Transient
     var researchedTechnologies = ArrayList<Technology>()
     @Transient
@@ -42,6 +43,7 @@ class TechManager {
     /** For calculating Great Scientist yields - see https://civilization.fandom.com/wiki/Great_Scientist_(Civ5)  */
     var scienceOfLast8Turns = IntArray(8) { 0 }
     var scienceFromResearchAgreements = 0
+    /** This is the lit of strings, which is serialized */
     var techsResearched = HashSet<String>()
 
     /** When moving towards a certain tech, the user doesn't have to manually pick every one. */

core/src/com/unciv/logic/map/MapUnit.kt

@@ -495,13 +495,7 @@ class MapUnit {
                 .forEach { unit -> unit.destroy() }
     }
 
-    fun removeFromTile() {
+    fun removeFromTile() = currentTile.removeUnit(this)
-        when {
-            type.isAirUnit() -> currentTile.airUnits.remove(this)
-            type.isCivilian() -> getTile().civilianUnit = null
-            else -> getTile().militaryUnit = null
-        }
-    }
 
     fun moveThroughTile(tile: TileInfo) {
         if (tile.improvement == Constants.ancientRuins && civInfo.isMajorCiv())

core/src/com/unciv/logic/map/TileInfo.kt

@@ -483,7 +483,19 @@ open class TileInfo {
     }
 
     fun stripUnits() {
-        for (unit in this.getUnits()) unit.removeFromTile()
+        for (unit in this.getUnits()) removeUnit(unit)
+    }
+
+
+    /** If the unit isn't in the ruleset we can't even know what type of unit this is! So check each place
+     * This works with no transients so can be called from gameInfo.setTransients with no fear
+     */
+    fun removeUnit(mapUnit: MapUnit){
+        when {
+            airUnits.contains(mapUnit) -> airUnits.remove(mapUnit)
+            civilianUnit == mapUnit -> civilianUnit = null
+            else -> militaryUnit = null
+        }
     }
 
     fun startWorkingOnImprovement(improvement: TileImprovement, civInfo: CivilizationInfo) {