Add meaningful message to error raised on missing attribute
Add meaningful message to error raised on missing attribute

bholzer/rabl,infertux/rabl,nesquena/rabl,zoyi/rabl,infertux/rabl,Jyaasa/rabl,zoyi/rabl,sideci-sample/sideci-sample-rabl,Jyaasa/rabl,nesquena/rabl,zoyi/rabl,nesquena/rabl,sideci-sample/sideci-sample-rabl,Jyaasa/rabl,infertux/rabl,bholzer/rabl,bholzer/rabl