The feature of `errors.Join()` is specific to Go 1.20+. Many calls to it are made from zabbix_agent2.go. 

Regardless, use of these is considered a bad practice by golang experts:

https://dev.to/wspowell/avoid-go120-error-handling-27hd

However, the real question is: why introduce a "feature" that isn't really helpful but breaks backward compatibility with go 1.19? 

You might ask "why remain compatible with go 1.19"? Answer: older systems need it. For example: RHEL7/CentOS7. Who care that it's soon EOL. Upgrading these systems is "non-trivial" and not worth the effort, usually.