LGTM warning fix

examples/webgl_geometry_terrain_fog.html

@@ -30,15 +30,10 @@
 			import { ImprovedNoise } from './jsm/math/ImprovedNoise.js';
 
 			var container, stats;
-
 			var camera, controls, scene, renderer;
-
 			var mesh, texture;
 
 			var worldWidth = 256, worldDepth = 256;
-			var worldHalfWidth = worldWidth / 2;
-			var worldHalfDepth = worldDepth / 2;
-
 			var clock = new THREE.Clock();
 
 			init();