I was seeing an identical error on a heavily modded save file, and removing Factorissimo2 fixed the crash. I was not running railway-painter.

I'm also seeing this PNG error on Ubuntu 17.10. Downgrading to Factorio 0.16.16 manually has fixed things.

I would be really sad to lose my bots. Please don't nerf them. My major uses of bots: Construction bots and blueprints. Personally, I find that Factorio without construction bots and blueprints is a lot less fun, at least after the first playthrough. Factorio is all about scalable power and progress...

Wow, the Factorio modding API is fun! I've been having fun working on game-balancing a late-game nuclear tank (see "Nuclear Vehicles" on the mod portal) with a rocket launcher and an equipment grid. And I'd like to do something similar with locomitives: a nuclear-powered, armored locomotiv...