Steps to reproduce:

1. Open scheduled reports edit form
2. Turn on network throttling
3. Click Test
4. Click Cancel

Result:

Scheduled reports form is closed, but test form is opened.

Expected:
User shouldn't be able to click Cancel (as 7.0 has) or there should be something preventing closing the pop-up.

Other cases:

• Item edit form (7.4+):
  • Test button in page footer
  • JS error when call test from preprocessing tabs. There also isn't anything indicating loading as clicking Test button does while validation is done.
• Users > Authentication (master):
  • LDAP settings: click Test. This is possible case, that uses same logic, but can't reproduce directly because none of the fields have validation which requires request to be made. 
• Item edit form > Preprocessing tab (7.4+):
  • Setup several steps
  • Click "Test all steps" and immediately click on the "Remove" buttons for one or several Preprocessing steps
  • The new popup displays an error due to a missing key. 

Undefined array key "type" [zabbix.php:17 → require_once() → ZBase->run() → ZBase->processRequest() → CController->run() → CControllerPopupItemTestEdit->checkInput() → CControllerPopupItemTestEdit->checkTestInputs() → normalizeItemPreprocessingSteps() in include/items.inc.php:1770]Invalid parameter "/1": the parameter "type" is missing. 

• Script edit form in scope of ZBXNEXT-9745