The body is:
{"message":"'10.10.10.10' is a bogon (Private network) IP address."}
And the status code is 423 Locked as you can see in the error, just like you expect.
you probably did:
response = HTTP.get(...) # throws
response == nothing # Nani !?
You can’t expect a return value when a function throws an exception.
Use: HTTP.get(...; status_exception=false) to not throw.