If a Git commit failed because of a problem with the editor:
git commit error: There was a problem with the editor 'vi'. Please supply the message using either -m or -F option.
It can be a pain to remember the commit message again.
But if you saved the message before quitting the editor, it should still be there:
This means that you can commit without having to rewrite the message:
git commit -m "$(cat .git/COMMIT_EDITMSG)"