Uninitialized data could be sent to trapper

Steps to reproduce:
1. Create discovery rule with active proxy and with TCP check, Zabbix agent "agent.hostname" and Zabbix agent "system.uname" checks. Set ports range to 10048-10052 for all checks.
Set update interval to some relatively small value (e.g. 20s).
2. Create discovery action to add host when discovery status is UP.
3. Start server, start proxy, no agent is necessary.

Result:
See "trapper got" log on the server side. Periodically during proxy discovery data receiving a batch of garbage data is noted on trapper input.