How to check if command had any output (zsh)

I want to print a new line after a command if it had any output (I hope that this will make it more readable once my terminal starts scrolling).

I found this:

precmd() {
    precmd() {
        print ""
    }
}

Which works, but obviously prints line after every command.

And also this:

precmd () {                        
    exec 2>&- >&-
    lastline=$(tail -1 ~/.command.out)
    sleep 0.1
    exec > /dev/tty 2>&1
}

preexec() {
    exec > >(tee ~/.command.out&)
}

And tried to modify it, but it "breaks" the output (and makes vim un-usable) even w/o my modificatons.