Fix null reference on non-HTTP response exception
Fix null reference on non-HTTP response exception

lydonchandra/RestSharp,RestSharp-resurrected/RestSharp,who/RestSharp,felipegtx/RestSharp,PKRoma/RestSharp,wparad/RestSharp,periface/RestSharp,cnascimento/RestSharp,eamonwoortman/RestSharp.Unity,dmgandini/RestSharp,rucila/RestSharp,dgreenbean/RestSharp,haithemaraissia/RestSharp,KraigM/RestSharp,jiangzm/RestSharp,chengxiaole/RestSharp,fmmendo/RestSharp,uQr/RestSharp,dyh333/RestSharp,wparad/RestSharp,restsharp/RestSharp,amccarter/RestSharp,SaltyDH/RestSharp,mattleibow/RestSharp,mwereda/RestSharp,rivy/RestSharp,kouweizhong/RestSharp,huoxudong125/RestSharp,benfo/RestSharp,mattwalden/RestSharp