resolution passed should be an object instead of a number as per the EquirectangularToCubeGenerator.js file
@@ -128,7 +128,7 @@
texture.encoding = THREE.sRGBEncoding;
- var cubemapGenerator = new THREE.EquirectangularToCubeGenerator( texture, 512 );
+ var cubemapGenerator = new THREE.EquirectangularToCubeGenerator( texture, { resolution: 512 } );
var cubeMapTexture = cubemapGenerator.update( renderer );
var pmremGenerator = new THREE.PMREMGenerator( cubeMapTexture );