Change directory in Terminal if working folder moved to Trash (in interactive shell)?
No, there's no way for Zsh to automatically notice that while you are not actively using it.
But what does it matter? You can just type cd to go back to your home folder.
Update
All right, here's a real solution that I've tested and it works. Thanks to @nohillside for the encouragement!
autohome() {
  # If the present working dir doesn't exist...
  if [[ ! -d $PWD ]]; then
    # Go back to ~
    cd $HOME

    # If the line editor is active, redraw the prompt.
    zle &amp;&amp; zle .reset-prompt
  fi
}

# This will call the function above as soon as you start typing.
autoload -Uz add-zle-hook-widget
add-zle-hook-widget line-pre-redraw autohome