migration.v17: add nil error check
migration.v17: add nil error check

chriswatt/gogs,cgars/gogs,ForxaCoLab/forxa,wangjild/gogs,linquize/gogs,linquize/gogs,pikacloud/pikacode,pikacloud/pikacode,wangjild/gogs,xaionaro/gogs,cgars/gogs,gogits/gogs,chriswatt/gogs,mukaiu/gogs,cgars/gogs,dancewing/gogs,mukaiu/gogs,linquize/gogs,wangjild/gogs,dancewing/gogs,chriswatt/gogs,mukaiu/gogs,dancewing/gogs,xaionaro/gogs,ForxaCoLab/forxa,ForxaCoLab/forxa,pikacloud/pikacode,xaionaro/gogs,gogits/gogs,dancewing/gogs,gogits/gogs