1. Run local http serer at the project root
   e.g. > cd path/to/vanillajs-datepicker
        > http-server ./
2, Using Chromium-based browser, open this test file through the local http serer
   e.g. http://localhost:8080/test/non-automated/for-issue-144-autofill/index.html
3. Type a date in the input field (do not choose from Datepicker), and submit
4. Open the browser's console in Dev Tools
5. Click the input field, and select a date from the autofill
5. See if no error is output in the console