angle's&bob's mod
I set building cycle to 1 tick.
I upgrade(replace) iron-pipe to copper-pipe with drag
It was okay to replace a small amount of pipes, but I try to replace a large amount of pipes, and I get this error. https://imgur.com/RF8wP5J
Thanks for the report.
It's something related the direction of the entity, which can be nil obviously. This is a quite new feature, so it might still contain some edge case problems.
