[BUG] [Ruby] client raises error on file download

Created by: tpltn

Description

Hey! There is a method def download_file(request), which should write a message to the log when request completes with tempfile path. But if request fails, there are no tempfile:

    def download_file(request)
      # ...
      request.on_complete do |response|
        tempfile.close if tempfile
        @config.logger.info "Temp file written to #{tempfile.path}, please copy the file to a proper folder "\
                            "with e.g. `FileUtils.cp(tempfile.path, '/new/file/path')` otherwise the temp file "\
                            "will be deleted automatically with GC. It's also recommended to delete the temp file "\
                            "explicitly with `tempfile.delete`"
      end
    end

openapi-generator version

latest master 94152c4d

Steps to reproduce

1. Generate Ruby (Typhoeus or Faraday, doesn't matter) client
2. Make API, which returns error or which is unavailable
3. Try to download file with generated client

Suggest a fix/enhancement

Write a log message if tempfile exists. I'll make PR in a moment