fix memory leak

src/main.cpp

@@ -115,8 +115,9 @@ int main(int argc, char *argv[]) {
                 p.y > floor(camera.position.y / 3.2f) + camera.renderDistance ||
                 p.z > floor(camera.position.z / 3.2f) + camera.renderDistance)
             {
-                if (c->second->mesh != nullptr) delete c->second->mesh;
                 world->chunksWithMeshes.erase(p);
+                delete c->second->mesh;
+                c->second->mesh = nullptr;
             }
         }