CubemapGenerator: Ensure options is never undefined

examples/js/loaders/EquirectangularToCubeGenerator.js

@@ -86,6 +86,8 @@ THREE.CubemapGenerator.prototype.fromEquirectangular = function ( texture, optio
 
 	scene.add( mesh );
 
+	options = options || {};
+
 	var resolution = options.resolution || 512;
 
 	var params = {
@@ -120,6 +122,8 @@ THREE.EquirectangularToCubeGenerator = ( function () {
 
 	var EquirectangularToCubeGenerator = function ( sourceTexture, options ) {
 
+		options = options || {};
+
 		this.sourceTexture = sourceTexture;
 		this.resolution = options.resolution || 512;