Exit with status code 1 if no endpoints found

[RobinBoers]

This allows people to write the following kind of code:

if  wm "$1" && prompt -y "Send mentions for these URLs?"; then
    wm "$1" --send
fi

Instead of this monstrosity:

out="$(wm "$1")"
echo "$out"

if [ "$out" != "No webmention endpoints found on 1 entries found (try increasing with --limit N)" ] && prompt -y "Send mentions for these URLs?"; then
  wm "$1" --send
fi

[remy]

Good change. Though, should it also exit(1) with the --send flag too?

[RobinBoers]

As I see it, trying to send webmentions but failing to do so is a failure, so it should exit(1). But I'm open for other ideas too, what do you think?