# File lib/chef-config/mixin/credentials.rb, line 84
      def load_credentials(profile = nil)
        profile = credentials_profile(profile)
        config = parse_credentials_file
        return if config.nil? # No credentials, nothing to do here.
        if config[profile].nil?
          # Unknown profile name. For "default" just silently ignore, otherwise
          # raise an error.
          return if profile == "default"
          raise ChefConfig::ConfigurationError, "Profile #{profile} doesn't exist. Please add it to #{credentials_file}."
        end
        apply_credentials(config[profile], profile)
      end