Scheduled Report - Timezone field validation missing

Steps to reproduce:

1. Open the Create Scheduled Report form
2. Add a valid name. Press Continue. The user is redirected to the Scheduler section
3. Leave the Timezone field (required) blank. Click Continue

Expected result: The continue button is disabled while the required field is not filled in.

Actual result: A user can move to the Condition section leaving the required Timezone field blank. The screen crashes on the next step without an option to return to the previous screen.