fix `lxc`'s error messages to be more helpful
fix `lxc`'s error messages to be more helpful

Signed-off-by: Tycho Andersen <10c18fcb898ee6b17d6575d444b125d10b3f4d6a@canonical.com>

benaryorg/lxd,mikemccracken/lxd,benaryorg/lxd,stgraber/lxd,erikmack/lxd,beni55/lxd,yura-pakhuchiy/lxd,atxwebs/lxd,jsavikko/lxd,benaryorg/lxd,lxc/lxd,techtonik/lxd,smoser/lxd,sl1pm4t/lxd,achanda/lxd,ericsnowcurrently/lxd,rcj4747/lxd,atxwebs/lxd,lxc/lxd,lxc/lxd,chrisglass/lxd,georghopp/lxd,jensg-st/lxd,smoser/lxd,ericsnowcurrently/lxd,Skarlso/lxd,erikmack/lxd,akshaykarle/lxd,georghopp/lxd,jensg-st/lxd,hallyn/lxd,akshaykarle/lxd,rrva/lxd,stgraber/lxd,mjeanson/lxd,beni55/lxd,pcdummy/lxd,rcj4747/lxd,rcj4747/lxd,sl1pm4t/lxd,jumpstarter-io/lxd,yura-pakhuchiy/lxd,ericsnowcurrently/lxd,lxc/lxd,jumpstarter-io/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,jumpstarter-io/lxd,sl1pm4t/lxd,akshaykarle/lxd,yura-pakhuchiy/lxd,rrva/lxd,smoser/lxd,Malizor/lxd,mjeanson/lxd,stgraber/lxd,erikmack/lxd,lxc/lxd,Malizor/lxd,beni55/lxd,Malizor/lxd,ollie314/lxd,achanda/lxd,mikemccracken/lxd,stgraber/lxd,hallyn/lxd,ollie314/lxd,pcdummy/lxd,lxc/lxd,dustinkirkland/lxd,ollie314/lxd,stgraber/lxd,hallyn/lxd,dustinkirkland/lxd,georghopp/lxd,pcdummy/lxd,Skarlso/lxd,atxwebs/lxd,jsavikko/lxd,Skarlso/lxd,dustinkirkland/lxd,mjeanson/lxd,lxc/lxd,mikemccracken/lxd,stgraber/lxd,achanda/lxd,techtonik/lxd,hallyn/lxd,rrva/lxd,techtonik/lxd,chrisglass/lxd,jensg-st/lxd,jsavikko/lxd,chrisglass/lxd,atxwebs/lxd,Skarlso/lxd