Use implicit sharing when getting categories from Session class

src/base/bittorrent/session.cpp

@@ -585,7 +585,7 @@ QStringList Session::expandCategory(const QString &category)
     return result;
 }
 
-const QStringMap &Session::categories() const
+QStringMap Session::categories() const
 {
     return m_categories;
 }

src/base/bittorrent/session.h

@@ -201,7 +201,7 @@ namespace BitTorrent
         // returns category itself and all top level categories
         static QStringList expandCategory(const QString &category);
 
-        const QStringMap &categories() const;
+        QStringMap categories() const;
         QString categorySavePath(const QString &categoryName) const;
         bool addCategory(const QString &name, const QString &savePath = "");
         bool editCategory(const QString &name, const QString &savePath);

src/webui/api/synccontroller.cpp

@@ -446,7 +446,7 @@ void SyncController::maindataAction()
     data["torrents"] = torrents;
 
     QVariantHash categories;
-    const auto &categoriesList = session->categories();
+    const QStringMap categoriesList = session->categories();
     for (auto it = categoriesList.cbegin(); it != categoriesList.cend(); ++it) {
         const QString &key = it.key();
         categories[key] = QVariantMap {

src/webui/api/torrentscontroller.cpp

@@ -1077,8 +1077,8 @@ void TorrentsController::removeCategoriesAction()
 void TorrentsController::categoriesAction()
 {
     QJsonObject categories;
-    const auto categoriesList = BitTorrent::Session::instance()->categories();
+    const QStringMap categoriesMap = BitTorrent::Session::instance()->categories();
-    for (auto it = categoriesList.cbegin(); it != categoriesList.cend(); ++it) {
+    for (auto it = categoriesMap.cbegin(); it != categoriesMap.cend(); ++it) {
         const auto &key = it.key();
         categories[key] = QJsonObject {
             {"name", key},