fix world deletion & fix segfault on attempt to reset content when world is open

src/logic/EngineController.cpp

@@ -34,9 +34,10 @@ EngineController::EngineController(Engine& engine) : engine(engine) {
 void EngineController::deleteWorld(const std::string& name) {
     fs::path folder = engine.getPaths().getWorldFolderByName(name);
 
-    auto deletion = [&]() {
+    auto deletion = [this, folder]() {
         logger.info() << "deleting " << folder;
         fs::remove_all(folder);
+        engine.getGUI()->getMenu()->back();
     };
 
     if (engine.isHeadless()) {

src/logic/scripting/lua/libs/libcore.cpp

@@ -36,6 +36,9 @@ static int l_load_content(lua::State* L) {
 }
 
 static int l_reset_content(lua::State* L) {
+    if (level != nullptr) {
+        throw std::runtime_error("world must be closed before");
+    }
     engine->resetContent();
     return 0;
 }