Description:
When using the "FortiGate by HTTP" template, SD-WAN member discovery fails if the SD-WAN health check on the FortiGate device is set to "check all sd-wan members". The discovery process seems to depend on the health check configuration, leading to incomplete or failed discovery under this setup.

Error after Discovery:

Preprocessing failed for: {"data":{},"error":"TypeError: cannot read property 'length' of undefined."}
1. Failed: cannot extract value from json by path "$.data.member_lld": no data matches the specified path

Steps to reproduce:

1. Apply the "FortiGate by HTTP" template to a FortiGate device.
2. Configure the SD-WAN health check on the FortiGate to "check all sd-wan members".
3. Trigger SD-WAN member discovery in Zabbix.
4. Notice that SD-WAN members are not discovered or the discovery is incomplete.

Result:
See attached file "health-check.json". Health check "Default_DNS" has "All SD-WAN members" configured, health check "ping_pub_dns" has the individual members selected.

Expected:
Health checks with "All SD-WAN members" set should not result in discovery errors. 

Suggested Fix:
Modify the SD-WAN member discovery logic in the template to avoid dependency on the health check configuration. It should directly query SD-WAN member details independently to ensure all members are correctly discovered.