Error for Specular Aliasing PG

Hi,

is it know issue about shader error on Specular Aliasing PG from Master Physically Based Rendering ?

BJS - [15:07:07]: Error: Validation Failed: Sampler error:
  Samplers of different types use the same texture image unit.
   - or -
  A sampler's texture unit is out of range (greater than max allowed or negative).

Can give more information if needed.

OS: Mac Desktop on chrome and safari.