URI::Generic#check_user

# File tmp/rubies/ruby-4.1.0-preview1/lib/uri/generic.rb, line 393
def check_user(v)
  if @opaque
    raise InvalidURIError,
      "cannot set user with opaque"
  end

  return v unless v

  if parser.regexp[:USERINFO] !~ v
    raise InvalidComponentError,
      "bad component(expected userinfo component or user component): #{v}"
  end

  return true
end