To not do network activity in init or global variables creation

[AskAlexSharov]

seems next global variable creation:

var defaultClient = New()

Does network activity:
NewUserConfig -> net.ResolveTCPAddr("tcp", fmt.Sprintf("[%s]:0", address))
and then mutating net.DefaultResolver.Dial

seems it's not thread-safe in golang (in OS's C libraries which used by golang).

And on some OS this race-condition caused crash: erigontech/erigon#12570

We still collecting evidences: i may be a bit wrong