Adding a Break While Creating a Shift
Adding a valid break while creating a new shift persists it
On the new shift form,
fill in the shift's location, user, and times.
Click Add Break to add a blank break row, before ever submitting the form.
Fill in the break's start and end time, within the shift's time range.
Submit the new shift form.
The break was persisted along with the new shift.

A break outside the new shift's time range shows an error
On the new shift form fill in the shift's location, user, and times. Click Add Break to add a blank break row. Enter a break start time before the shift starts. An error is shown on the row.