Merge pull request #21188 from ZehMatt/fix-21171

Fix #21171: Crash creating entities with no slots available

distribution/changelog.txt

@@ -4,6 +4,7 @@
 - Improved: [#20951] Activate OpenRCT2 window after using native file dialog on macOS.
 - Fix: [#21145] [Plugin] setInterval/setTimeout handle conflict.
 - Fix: [#21158] [Plugin] Potential crash using setInterval/setTimeout within the callback.
+- Fix: [#21171] [Plugin] Crash creating entities with no more entity slots available.
 - Fix: [#21178] Inca Lost City’s scenario description incorrectly states there are height restrictions.
 
 0.4.7 (2023-12-31)

src/openrct2/entity/EntityRegistry.cpp

@@ -341,11 +341,14 @@ EntityBase* CreateEntity(EntityType type)
 
     if (EntityTypeIsMiscEntity(type))
     {
-        // Misc sprites are commonly used for effects, if there are less than MAX_MISC_SPRITES
-        // free it will fail to keep slots for more relevant sprites.
-        // Also there can't be more than MAX_MISC_SPRITES sprites in this list.
-        uint16_t miscSlotsRemaining = MAX_MISC_SPRITES - GetMiscEntityCount();
-        if (miscSlotsRemaining >= _freeIdList.size())
+        // Misc sprites are commonly used for effects, give other entity types higher priority.
+        if (GetMiscEntityCount() >= MAX_MISC_SPRITES)
+        {
+            return nullptr;
+        }
+
+        // If there are less than MAX_MISC_SPRITES free slots, ensure other entities can be created.
+        if (_freeIdList.size() < MAX_MISC_SPRITES)
         {
             return nullptr;
         }

src/openrct2/scripting/bindings/world/ScMap.cpp

@@ -233,6 +233,11 @@ namespace OpenRCT2::Scripting
     DukValue createEntityType(duk_context* ctx, const DukValue& initializer)
     {
         TEntityType* entity = CreateEntity<TEntityType>();
+        if (entity == nullptr)
+        {
+            // Probably no more space for entities for this specified entity type.
+            return ToDuk(ctx, undefined);
+        }
 
         auto entityPos = CoordsXYZ{ AsOrDefault(initializer["x"], 0), AsOrDefault(initializer["y"], 0),
                                     AsOrDefault(initializer["z"], 0) };