Krun fails to run when the krun user group already exists

[fsfod]

If krun is interrupted starting up often when you try to run it again it will fail with the error:

[2018-03-14 18:11:21: ERROR] Command failed: '/usr/bin/sudo -u root useradd -m krun'
stdout:

stderr:
useradd: group krun exists - if you want to add this user to that group, use -g.

This is made worse by the fact you won't see the error until the temperature wait delay has elapsed and there is no email sent for the error either.

[ltratt]

A quick thought: is the right approach to simply ignore the error (it exists -- job's a good 'un); or to more carefully clean up when an error happens? I wonder if both are a little harder to do than they first look...