Steps to reproduce:

1. Enable history override for trends only
2. Navigate and create some dashboard with item widget
3. On screen you can see message:

4. A non-numeric value encountered [zabbix.php:17 → require_once() → ZBase->run() → ZBase->processRequest() → CController->run() → Widgets\Item\Actions\WidgetView->doAction() → Widgets\Item\Actions\WidgetView->getItemValues() → Widgets\Item\Actions\WidgetView->addDataSource() → CItemHelper::addDataSource() in include/classes/helpers/CItemHelper.php:366] 

   With history only or both overrides Zabbix frontend working as expected.

Result:

Expected:
No error about non-numeric value