headers function gives incorrect error message when code not provided #349
Description
Observed behavior
The headers function tests for a non-default code or description paired with a default code or description.
In either case it throws an InvalidArgumentError saying "'description' is required". This is incorrect and misleading when it is the code that is missing.
Expected behavior
It should provide a different error messages depending on what is missing or simply state that 'both code and description are required' as it did before.
Server and client version
nats-core version 3.2.0
Host environment
node
Steps to reproduce
call the header function with undefined code and description text