validation issue while enabling CFS

[Anupam-dagar]

Describe the bug

While enabling CFS, if one of the field is empty and we click outside, it gives the expected validation error but this error won't go even on filling up the correct values. Also the error message is wrong for CFS end time.

To Reproduce
Steps to reproduce the behaviour:

1. Go to '/events/event_id/edit/sessions-speakers'
2. Enable session & speakers
3. Empty the end date value
4. See error

Expected behaviour

Error should go away once it has been resolved. Also the correct error message should be shown.
Screenshots