add null check for describelayer response
add null check for describelayer response

flamingo-geocms/flamingo,mvdstruijk/flamingo,B3Partners/flamingo,B3Partners/flamingo,mvdstruijk/flamingo,flamingo-geocms/flamingo,mvdstruijk/flamingo,B3Partners/flamingo,mvdstruijk/flamingo,B3Partners/flamingo,flamingo-geocms/flamingo,flamingo-geocms/flamingo