HTTP Error 404 when run without --date parameter

[CaptSolo]

When get_data.py is run without --date parameter (default: current date) the script may fail with the 404 Not Found error.

It would be good to print a helpful notification in case this happens. While there is a code comment saying data is available after midnight UTC, the issue [of users getting the exception + stack trace] still remains.

For users in UTC+x timezones script (w/o --date param) will always fail (because when time approaches midnight UTC it is already the next date in their timezone).