Nicer error when NPN isn't available
Nicer error when NPN isn't available

layerhq/cowboy,grahamrhay/cowboy,binarin/cowboy,acrispin/cowboy,kivra/cowboy,paulperegud/cowboy,imdeps/cowboy,callsign-core/cowboy_hybi00,bobos/ecweb,bsmr-erlang/cowboy,yangchengjian/cowboy,pap/cowboy,rabbitmq/cowboy,dangjun625/cowboy,turtleDeng/cowboy,hairyhum/cowboy,ninenines/cowboy,cad627/cowboy,omusico/cowboy,K2InformaticsGmbH/cowboy,callsign-core/cowboy_hybi00,nviennot/cowboy,noname007/cowboy,cad627/cowboy,odo/cowboy,manastech/cowboy,sile/cowboy,binarin/cowboy,Reimerei/cowboy,yangchengjian/cowboy,CrankWheel/cowboy,manastech/cowboy,layerhq/cowboy,276361270/cowboy