[0.17.79] Crash loading save without nanotorio mod, "Build check failed"

[PyroFire]

the .log seems to suggest something about the splitters being a bad size.

I was expecting some sort of error message while trying to load the save, rather than an engine crash.

https://mods.factorio.com/mod/nanotorio

[Rseding91]

I can fix this, but you aren't going to like the fix.

Basically splitters can never be not 2 tiles wide. If you ever break that, it brakes like this when you remove the mod(s).

In fact, I think everything just ends up broken when splitters aren't 2 tiles wide. They are built at a core level with that assumption in mind.

[PyroFire]

I was more thinking about the game itself having crashed as the issue instead of throwing an in-game error and preventing the "corrupt" save from being loaded.
Errors were pretty much expected / guaranteed in this situation, and i'm sure the belts aren't the only ones.

It makes me think about what might happen if you change the size of a prototype and try to migrate it over previous saves.

[Rseding91]

In general changing prototype bounding box sizes is fine. The game handles it. For belt entities they aren't meant to ever have more than 1 on a given tile. By c hanging the splitter it breaks the "left tile, right tile" logic and you end up with a splitter on 1 tile. Then you build a belt next to it, and change the sizes back and now the splitter and belt are on the same tile.

Splitters are special in that they are belt-entities but are meant to touch and control 2 tiles. Everything else just touches and controls the 1 tile their center point sits on.