fix: Remove duplicate constants and add null check for updatePhysicsObjects

js/elements/physics_objects.js

@@ -1,7 +1,5 @@
 // Physics objects (square, circle, triangle)
-const SQUARE = 16;
-const CIRCLE = 17;
-const TRIANGLE = 18;
+// Constants are already defined in constants.js
 
 // Physics object properties
 const PHYSICS_OBJECT_COLORS = ['#FF5733', '#33FF57', '#3357FF', '#F3FF33', '#FF33F3'];

js/main.js

@@ -64,6 +64,11 @@ window.onload = function() {
     
     // Start the simulation loop
     requestAnimationFrame(simulationLoop);
+    
+    // Initialize physics variables
+    window.physicsUpdateRate = 16; // ms between physics updates
+    window.lastPhysicsTime = 0;
+    window.fireUpdateCounter = 0;
 };
 
 function resizeCanvas() {

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();