No error message when saving invalid "Time range"

We had a Teaching Assistant complaining that the scheduler was not saving her repeating slots she was creating.

The problem was that the "Time range" she was using was 12:45 to 02:00. She thought 02:00 meant 2pm. However, the real problem was that when she clicked "Save changes" it appeared that nothing happened.

What is expected is that there would be an error message indicating the invalid time range so she can correct it.