fix: add thread safety for cave and river path mutexes

include/Cubed/gameplay/cave_carver.hpp

@@ -17,11 +17,13 @@ public:
 
     int cave_sum() const;
     float& cave_probability();
+    std::shared_mutex& path_mutex();
 
 private:
     CaveHashMap m_paths;
     unsigned m_seed = 0;
     Random m_random;
     float m_cave_probability = 0.035f;
+    std::shared_mutex m_path_mutex;
 };
 } // namespace Cubed

include/Cubed/gameplay/river_worm.hpp

@@ -12,6 +12,7 @@ class RiverWorm {
 
 public:
     RiverWorm();
+    ~RiverWorm();
     RiverHashMap& paths();
     void init(unsigned world_seed);
     void reload(unsigned world_seed);
@@ -21,12 +22,14 @@ public:
 
     int river_sum() const;
     float& river_probability();
+    std::shared_mutex& paths_mutex();
 
 private:
     RiverHashMap m_paths;
     unsigned m_seed = 0;
     Random m_random;
     float m_probability = 0.01f;
+    std::shared_mutex m_paths_mutex;
 };
 
 }; // namespace Cubed

include/Cubed/gameplay/world.hpp

@@ -104,6 +104,7 @@ private:
 
     void submit_new_chunks();
     void poll_finished_chunks();
+    void wait_all_chunk_tasks();
 
 public:
     World();

include/Cubed/tools/thread_pool.hpp

@@ -48,7 +48,14 @@ public:
         for (auto& w : m_workers) {
             w.request_stop();
         }
+
         m_cv.notify_all();
+
+        for (auto& w : m_workers) {
+            if (w.joinable()) {
+                w.join();
+            }
+        }
     }
     template <typename F> auto enqueue(F&& f) {