"If you decide to kdz back to stock, make sure that you restored a stock backup in twrp before you kdz!"..
well what if i never made a backup in twrp??
Then it's probably time you started thinking about taking backups of your stock rom before flashing custom roms to have a fallback. That's a general good practice for any phone you have. I usually just assume that everyone takes backups as a precaution.
Even if you don't want to store the backup on your SD card to save space for other things, you can always use twrp to take a backup and copy it to your PC, or the new twrp 3.1 that is linked to in the op supports using a desktop tool to save backups directly to your pc.
You might get lucky and be able to ask someone for a twrp backup of stock and flash that.
You can try to kdz back to stock but when I did it I bootlooped bad. Like real bad. Adb didn't work, and I could only get back into download mode and reflash the kdz just to reboot and have it bootloop on me again. Basically a soft brick. I had to flash a v10i kdz using lg flash tool 2014 and pull the usb cable as soon as it started flashing which left me only with download mode from v10i, and the rest of the partitions on my phone were completely blank and luckily I didn't hard brick it. I was then able to reflash a v20k kdz and thank God it worked. I would not recommend having to do that since there is the danger of perma bricking your phone. I got super lucky, you might not.
Hopefully since lineage 13 is using the same kernel as stock you'll be ok, but I can't say for sure. I was on lineage 14 with the nougat kernel that I had to hack together to get it to boot on our phones.
There's a lot we don't know about this phone and playing it safe is the best way to avoid a brick. Seriously in the future make backups and use those instead of the kdz route because we have lost a lot of people already due to bad flashes.
