I've sent you link to translog files in private message.
My Unclean shutdown I mean:
I hit power button on my desktop, which triggered ACPI shutdown. Waited until the computer shuts off. Relocated it to another room, pressed the power button and when home. Several hours later I've tried to connect to kibana and discovered that its index in unavailable and ES produced over 20GB of logs. I've checked the last log, saw the aforementioned exception and started to investigate.
The kibana index was fully functional before the shutdown.
Thank you very much again for looking into this.