Steps to reproduce:

1. Set up Zabbix server with PostgreSQL and TimescaleDB extension
2. Navigate to Hosts -> Items, mark an item and click Clear history and trends

Result:
Warning message is displayed, but there is no text in the popup.
Issue is present on Safari and Chrome.
No such problem observed if TimescaleDB extension is not added. 

Expected:
Warning message displayed with text "Clear history and trends of selected items?"