dev: add some input validation to {new,erase}-feature
dev: add some input validation to {new,erase}-feature

tserong/crowbar,crowbar/crowbar,rhafer/crowbar,aplanas/crowbar,toabctl/crowbar,MaximilianMeister/crowbar,vwallfahrer/crowbar,rhafer/crowbar,rsalevsky/crowbar,mmnelemane/crowbar,nkrinner/crowbar,dirkmueller/crowbar,crowbar/crowbar,dirkmueller/crowbar,aspiers/crowbar,aspiers/crowbar,MaximilianMeister/crowbar,rsalevsky/crowbar,vwallfahrer/crowbar,tserong/crowbar,nkrinner/crowbar,SUSE-Cloud/crowbar,rhafer/crowbar,aplanas/crowbar,SUSE-Cloud/crowbar,mmnelemane/crowbar,toabctl/crowbar