fix: Remove duplicate constants and add null check for updatePhysicsObjects

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() {