add chunk 'entities' flag

src/files/WorldRegions.cpp

@@ -360,7 +360,7 @@ void WorldRegions::put(Chunk* chunk, std::vector<ubyte> entitiesData){
         return;
     }
     bool lightsUnsaved = !chunk->flags.loadedLights && doWriteLights;
-    if (!chunk->flags.unsaved && !lightsUnsaved) {
+    if (!chunk->flags.unsaved && !lightsUnsaved && !chunk->flags.entities) {
         return;
     }
 
@@ -441,7 +441,11 @@ chunk_inventories_map WorldRegions::fetchInventories(int x, int z) {
     if (data == nullptr) {
         return nullptr;
     }
-    return json::from_binary(data, bytesSize);
+    auto map = json::from_binary(data, bytesSize);
+    if (map->size() == 0) {
+        return nullptr;
+    }
+    return map;
  }
 
 void WorldRegions::processRegionVoxels(int x, int z, const regionproc& func) {

src/voxels/Chunk.hpp

@@ -35,6 +35,7 @@ public:
         bool lighted: 1;
         bool unsaved: 1;
         bool loadedLights: 1;
+        bool entities: 1;
     } flags {};
 
     /// @brief Block inventories map where key is index of block in voxels array

src/voxels/Chunks.cpp

@@ -717,7 +717,7 @@ void Chunks::save(Chunk* chunk) {
             list.put(level->entities->serialize(entity));
         }
         if (!entities.empty()) {
-            chunk->flags.unsaved = true;
+            chunk->flags.entities = true;
         }
         worldFiles->getRegions().put(chunk, json::to_binary(root, true));
     }

src/voxels/ChunksStorage.cpp

@@ -66,6 +66,7 @@ std::shared_ptr<Chunk> ChunksStorage::create(int x, int z) {
 
         if (auto map = regions.fetchEntities(chunk->x, chunk->z)) {
             level->entities->loadEntities(std::move(map));
+            chunk->flags.entities = true;
         }
 
         chunk->flags.loaded = true;