Why maxconn value can have a negative value?



When negative value is given for maxconn(-1,-2…-9, 10.) parameter in global section of haproxy.cfg. It is observed that haproxy service starts with successful health check up of backend servers.
But when larger negative value is given then haproxy fails to start and Alert message is shown.

For eg set maxconn value as “-1” in global section of haproxy.cfg and haproxy service is started.
By using the command:- “echo “show info” | socat unix-connect:/var/run/haproxy.stat stdio”
Name: HAProxy
Version: 1.8.1
Release_date: 2017/12/03
Nbproc: 1
Ulimit-n: 30
Maxsock: 30
Maxconn: 4294967295
Hard_maxconn: 4294967295

Above output shows that maxconn value is “4294967295” which is taken randomly.
Is this a bug? If not then why haproxy behaves abnormally for these values?
Can we enhance the check for which will prompt user from not having a negative value of "maxconn"as done for others(such as “inter”)?