return error early if field PageType is nil
return error early if field PageType is nil

jamiehannaford/gophercloud,sti-jans/gophercloud,timbyr/gophercloud,jamiehannaford/gophercloud,DSpeichert/gophercloud,sti-jans/gophercloud,trumant/gophercloud,larsbutler/gophercloud,carolynvs/gophercloud,dudymas/gophercloud,jarosser06/gophercloud,dudymas/gophercloud,rackspace/gophercloud,clintonskitson/gophercloud,larsbutler/gophercloud,pratikmallya/gophercloud,timbyr/gophercloud,carolynvs/gophercloud,trumant/gophercloud,feiskyer/gophercloud,feiskyer/gophercloud,DSpeichert/gophercloud,rackspace/gophercloud,clintonskitson/gophercloud,pratikmallya/gophercloud,jarosser06/gophercloud