provide better error from Client#info when argument is nil
provide better error from Client#info when argument is nil

closes #131

vcgato29/heroku,sancopanco/heroku,rkh/heroku,duypq94/heroku,Faisalawanisee/heroku,rkh/heroku,greeca0204/heroku,macedo/heroku,heroku/heroku,vcgato29/heroku,rkh/heroku,greeca0204/heroku,duypq94/heroku,greeca0204/heroku,Faisalawanisee/heroku,vcgato29/heroku,dickeyxxx/heroku,Faisalawanisee/heroku,heroku/heroku,sancopanco/heroku,uhoh-itsmaciek/heroku,sancopanco/heroku,duypq94/heroku,gregburek/heroku,macedo/heroku,dickeyxxx/heroku,dickeyxxx/heroku,gregburek/heroku,heroku/heroku,macedo/heroku,uhoh-itsmaciek/heroku,gregburek/heroku