`skip_untranslated_strings` downloads empty keys

Describe the bug Downloading any language, when the key is not translated yet instead of skipping the key completely it will download it and put and empty string:

"translation-key": "",

To Reproduce Steps to reproduce the behavior:

1. Configuration file:

"project_id_env": "CROWDIN_PROJECT_ID"
"api_token_env": "CROWDIN_AUTH_TOKEN"
"base_path": "."
"base_url": "https://api.crowdin.com"

"preserve_hierarchy": true

files: [{
  "source": "app/javascript/react/features/localization/locales/en.json",
  "dest": "/project/%original_file_name%",
  "translation": "%original_path%/%two_letters_code%.json",
  "skip_untranslated_strings": true
}, {
  "source": "config/locales/en.yml",
  "dest": "/project/%original_file_name%",
  "translation": "%original_path%/%two_letters_code%.yml",
  "skip_untranslated_strings": true
}]

1. Execute CLI command: crowdin download --config .crowdin/crowdin.yml
2. See an error

Expected behavior There should not be any empty key in the downloaded file.

Environment:

• OS: Ubuntu
• Version 20.04.3 LTS

Screenshots If applicable, add screenshots to help explain your problem.

Additional context Add any other context about the problem here.

[ira-sem]

@SamPersson @barrerajl would it be possible to share the examples of the source files with us on [e-mail]?ans also specify there a project name

[zozulka]

Dear @TrixterTheTux, You are always welcome 😃