Steps to reproduce:

1. Start Zabbix server ang agent
2. Import the host -> test-host.yaml
3. Open Monitoring -> Hosts -> test -> graphs, validate that pie graph with function last is displayed
4. Open Data collection -> Hosts -> test -> Items
5. Open Item -> item1
6. Change the Type of information to Text, add preprocessing (Regular expression):

   Parameters: 1
   Output: text
   

7. Update the item
8. Open Monitoring -> Hosts -> test -> graphs

Result:
Console error is displayed, graph is broken
Error:

TypeError: abs(): Argument #1 ($num) must be of type int|float, string given in /home/zabbix/workspace/7.0/ui/include/classes/graphdraw/CPieGraphDraw.php:261
Stack trace:
#0 /home/zabbix/workspace/7.0/ui/include/classes/graphdraw/CPieGraphDraw.php(261): abs()
#1 /home/zabbix/workspace/7.0/ui/include/classes/graphdraw/CPieGraphDraw.php(636): CPieGraphDraw->selectData()
#2 /home/zabbix/workspace/7.0/ui/chart6.php(133): CPieGraphDraw->draw()
#3 {main}

See video:

Expected:
The expected result need to be confirmed with PO team. Currently the non-numeric data is passed for some functions of pie widget, which might cause the issues.
Most likely "No data" should be displayed, when item's type of information is changed to non-numeric one.