Steps to reproduce:

1. Example JSON data in Zabbix sender format:

   localhost trapper {"data":[{"general_params":[{"{specification}":"power","{group}":"1","{value}":"30018"},{"{specification}":"power","{group}":"3","{value}":"30017"},{"{specification}":"power","{group}":"2","{value}":"748"},{"{specification}":"power","{group}":"4","{value}":"747"}]}]}
   

1. JSONPath step:

   $..general_params.[?(@.specification=~"power")].first()
   

Result:
Preprocessing worker crashes, log attached.