Should be fine without. I just increased the size of the world but left the rad zone starting at the same point, so everything SHOULD be ok.
But... y'know... cross your fingers and hope.
That sounds like it's getting rid of the UMATextures folder for whatever reason, because that's normal if it's missing when you boot up. I'd make folder manually, let the game do it's thing (because it WILL be slow and laggy), reboot and see if it's fixed.
If it is, rename the old folder and download the new one from GitHub and see if that sorts it. If it doesn't, at least you have a backup.