This caught me out last week when I tried to update via cmd line and it failed (reactions plugin).
It caught me out again when my cmd line update failed again this morning (data explorer plugin).
I would very much welcome a warning on the cmd line before the update process starts, and then inevitably fails.
Twice in two weeks now my updates have failed and this has meant my Discourse is offline for the duration of time it takes me to debug the issue, edit configs, try again, etc - all while in a mild state of panic because everything is broken.