fix Block.rt and ItemDef.rt initialization

src/items/ItemDef.hpp

@@ -41,7 +41,7 @@ struct ItemDef {
         item_funcs_set funcsset {};
         blockid_t placingBlock;
         bool emissive = false;
-    } rt;
+    } rt {};
 
     ItemDef(const std::string& name);
     ItemDef(const ItemDef&) = delete;

src/voxels/Block.hpp

@@ -195,7 +195,7 @@ public:
         
         /// @brief picking item integer id
         itemid_t pickingItem = 0;
-    } rt;
+    } rt {};
 
     Block(const std::string& name);
     Block(std::string name, const std::string& texture);