Break Validation
A break outside the shift's time range shows an error
On the edit shift page
Enter a break start time before the shift starts and click Add Break.
An error is shown and no break is added.

A break that overlaps an existing break shows an error
On the edit shift page with an existing break
Enter a second break that overlaps the existing 12:00-12:30 break.
An error is shown and no second break is added.

Editing a break outside the shift's time range shows an error
On the edit shift page with an existing break Change the break's start time to before the shift starts and click Save. An error is shown and the break is unchanged.
Editing a break to overlap another break shows an error
On the edit shift page with two existing breaks Change the first break's time to overlap the second break (3:00-3:30 PM) and click Save. An error is shown and the break is unchanged.