fix: Remove duplicate constants and add null check for updatePhysicsObjects

js/physics.js

@@ -8,7 +8,9 @@ function updatePhysics(timestamp) {
     lastPhysicsTime = timestamp || 0;
     
     // Update physics objects
-    updatePhysicsObjects();
+    if (typeof updatePhysicsObjects === 'function') {
+        updatePhysicsObjects();
+    }
     
     // Get visible chunks
     const visibleChunks = getVisibleChunks();