Problem description: If browser item that uses Safari browser collects performance entries, for some actions (like logout) the script fails with the following response:

{"duration":6.568601846694946,"error":{"http_status":500,"code":"javascript error","message":"cannot collect performance data: A JavaScript exception occured: cannot serialize cyclic structures."},....

Full response: response.txt

Steps to reproduce:

1. Import the following host: browser_item_host_safari-1.yaml
2. Open user macros for this host and specify the name of Your branch and the address of the machine where You have Your Zabbix installed
3. Open configuration of the only item on this host
4. Execute test functionality for this item
5. Make sure that performance entries for open page and login marks are present and no errors are observed
6. Open the script of this item and uncomment performance data collection on logout action (line 34)
7. Execute test item functionality again

Result the previously mentioned error is returned along with performance data for "open page" and "login" marks.
Expected: Performance data for marks "open page", "login" and "logout" should be returned, no errors should be observed.

Result:
See screenshot...
See log file...
See memory dump...
Expected:
See screenshot....
See attached patch file...