fix ui elements overriding

src/frontend/UiDocument.cpp

@@ -45,7 +45,7 @@ std::shared_ptr<gui::UINode> UiDocument::get(const std::string& id) const {
     if (found == map.end()) {
         return nullptr;
     }
-    return found->second;
+    return found->second.lock();
 }
 
 const uidocscript& UiDocument::getScript() const {

src/frontend/UiDocument.hpp

@@ -19,7 +19,7 @@ struct uidocscript {
     bool onclose : 1;
 };
 
-using UINodesMap = std::unordered_map<std::string, std::shared_ptr<gui::UINode>>;
+using UINodesMap = std::unordered_map<std::string, std::weak_ptr<gui::UINode>>;
 
 class UiDocument {
     std::string id;