Frontend validation: Epic start date can be after epic end date if you click fast enough
The scope of this issue is the frontend changes resulting from the backend validation work done in #4002 (closed)
- After selecting a date outside of the valid date range (start after finish, or finish before start), the date picker should close and a spinner appear (during this time, the validation occurs)
- If there's an error, show an error message (see image below) and re-open the date picker so the user can select a different date
- The user can close the date picker by clicking outside of it or clicking the dropdown select. In this case, the error message disappears.