execution: properly check container.Exec return value
execution: properly check container.Exec return value

Signed-off-by: Akihiro Suda <ea940da7e429af3d0d0c18296cabd0112a36bad5@lab.ntt.co.jp>

mikebrow/containerd,dmcgowan/containerd,estesp/containerd,yuexiao-wang/containerd,xiekeyang/containerd,rajasec/containerd,containerd/containerd,miaoyq/containerd,crosbymichael/containerd,AkihiroSuda/containerd,miaoyq/containerd,thaJeztah/containerd,kunalkushwaha/containerd,kunalkushwaha/containerd,containerd/containerd,vdemeester/containerd,estesp/containerd,hqhq/containerd,lichao-mobanche/containerd,thaJeztah/containerd,vdemeester/containerd,docker/containerd,crosbymichael/containerd,chanezon/containerd,dmcgowan/containerd,mikebrow/containerd