lfs/tq: send error before terminating object
lfs/tq: send error before terminating object

Previously, decrementing the surrounding `sync.WaitGroup` allowed the
`q.errorc` channel to be closed before this send could occur. This racy
behavior introduced a send-on-closed-channel panic, which is fixed in this
commit.

bozaro/git-lfs,github/git-lfs,andyneff/git-lfs,andyneff/git-lfs,Jericho25/-git-lfs_miilkyway,aleb/git-lfs,bozaro/git-lfs,dakotahawkins/git-lfs,bozaro/git-lfs,aleb/git-lfs,github/git-lfs,Jericho25/-git-lfs_miilkyway,andyneff/git-lfs,Jericho25/-git-lfs_miilkyway,dakotahawkins/git-lfs,github/git-lfs,dakotahawkins/git-lfs,aleb/git-lfs