fix Engine::resetContent in headless mode

src/engine/Engine.cpp

@@ -401,8 +401,10 @@ void Engine::resetContent() {
     content.reset();
 
     langs::setup(resdir, langs::current->getId(), contentPacks);
-    loadAssets();
-    onAssetsLoaded();
+    if (!isHeadless()) {
+        loadAssets();
+        onAssetsLoaded();
+    }
 
     contentPacks = manager.getAll(basePacks);
 }

src/engine/Engine.hpp

@@ -108,6 +108,7 @@ public:
     /// @brief Load all selected content-packs and reload assets
     void loadContent();
 
+    /// @brief Reset content to base packs list
     void resetContent();
     
     /// @brief Collect world content-packs and load content