On power off error at line 580 in VBoxManageControlVM.cpp in 6.0.18

[Splarv]

I have automatic test system based on VirtualBox, which in infinite loop test VMs, for instance for power off. And now I see some rare error when power off VM. The error may be rare, but in the night run I got it twice. Looked like error at line 580 in VBoxManageControlVM.cpp. I didn't saw such error in 6.0.16. Screenshots are attached to the bug report.
https://www.virtualbox.org/ticket/19370

[mpack]

If you want the devs to take notice, make sure a zipped log is attached to the ticket. Otherwise it goes nowhere. Pictures are of little help, they do not substitute for a log.