refactor: PVS-Studio warnings fixes

src/frontend/ContentGfxCache.cpp

@@ -18,7 +18,7 @@ ContentGfxCache::ContentGfxCache(const Content* content, Assets* assets) : conte
     auto atlas = assets->get<Atlas>("blocks");
     
     for (uint i = 0; i < indices->blocks.count(); i++) {
-        Block* def = indices->blocks.get(i); //FIXME: Potential null pointer
+        auto def = indices->blocks.getWriteable(i); //FIXME: Potential null pointer
         for (uint side = 0; side < 6; side++) {
             const std::string& tex = def->textureFaces[side]; //-V522
             if (atlas->has(tex)) {

src/frontend/LevelFrontend.cpp

@@ -25,8 +25,8 @@ LevelFrontend::LevelFrontend(
         "block-previews"
     );
     controller->getBlocksController()->listenBlockInteraction(
-        [=](Player* player, glm::ivec3 pos, const Block* def, BlockInteraction type) {
-            auto material = level->content->findBlockMaterial(def->material);
+        [=](Player* player, glm::ivec3 pos, const Block& def, BlockInteraction type) {
+            auto material = level->content->findBlockMaterial(def.material);
             if (material == nullptr) {
                 return;
             }