fix nil carrier bug
fix nil carrier bug

bzz/circuit,lgscofield/circuit,mzdravkov/circuit,cgvarela/circuit,rranshous/circuit,cgvarela/circuit,ebookbug/circuit,mjolk/circuit,ebookbug/circuit,mjolk/circuit,mzdravkov/circuit,beni55/circuit,tonestuff/circuit,bzz/circuit,ebookbug/circuit,cgvarela/circuit,bzz/circuit,tonestuff/circuit,lgscofield/circuit,beni55/circuit,bzz/circuit,lgscofield/circuit,tonestuff/circuit,rranshous/circuit,mjolk/circuit,tonestuff/circuit,beni55/circuit,mzdravkov/circuit,mzdravkov/circuit,lgscofield/circuit,mjolk/circuit,rranshous/circuit,ebookbug/circuit,rranshous/circuit,cgvarela/circuit,beni55/circuit