zsh plugin for recovering lost commit message when `git commit` exits unsuccessfully

recovery.zsh

git() {

  setopt localtraps;
  trap "(){}" SIGHUP SIGINT SIGTERM

  commit=
  function clean_up() {
    unset commit; # declare it local first
    rm -f .git/COMMIT_EDITMSG_BAK
  }

  command git "$@";
  if (( $? != 0 )) && [[ $1 == "commit" ]]; then
    # Ignore commented lines while copying the commit message
    sed -n '/Please enter the commit message /q;p' .git/COMMIT_EDITMSG >! .git/COMMIT_EDITMSG_BAK
    commit="true" # don't export

    # Prompt the user in the next invocation of `git commit`
  elif [[ -z $commit ]] && [[ $1 == "commit" ]]; then # $commit is referenced but never set
    # TODO: At this point we have to interrupt the usual flow of `git commit`
    # and then proceed to avoid overwriting .git/COMMIT_EDITMSG
    read -q "Old commit message found. Do you wish to use it?" yn
    case $yn in
      [Yy]* ) git commit -F .git/COMMIT_EDITMSG_BAK; clean_up;;
      [Nn]* ) clean_up;; # function is undefined at this point in  the code (first call to git() in a given shell session)
      * ) echo "Please answer yes or no.";;
    esac
  fi
}