Please help reviewing mon-client

Hi,

mon-client was a candidate for the bug of the day today and thus I had a
look.  The autopkgtest never succeeded due to Perl syntax errors and I'm
actually wondering how that code could have been used at all.  I tried
my best (which is admittedly very less) but the autopkgtest keeps on
failing as you can see in Salsa CI[1].

If your time permits having a look I'd be very happy.

Kind regards
   Andreas.

[1] https://salsa.debian.org/debian/mon-client/-/jobs/7071136