Error on start

After removing this mod no error anymore.

small-parts aren't bob's mods things, I suggest you report the issue to Angel, however, it is very likely a Py issue... but that guy really does not care at all if his mods work with anybody elses, so, it's unlikely there'd be a fix if his mods are causing it.

Y'know what?
errors like this bug me. I mean, Things I can't fix being reported to me because it's other mods doing it bug me as a whole anyway, but, I can manage that.
This bug, in theory, I can do something about, so I just might.

My idea: write a function in my library mod that checks all ingredients of all recipes for duplicates. If they're found, merge them.
It can't happen in my own mods, as I use my library to add ingredients already, and that checks if it exists before it tries to add it, either discarding the second request, or adding the two amounts together if it is found, depending which version of the function is used.
Only problem is it might slow down the loading of the game.

I can write the data-final-fixes for fixing this bug by myself, just to add all-mods-compatibility, but I got this issue by the mod testing.
Such script must be (can be) by all mods and just do nothing by compatible mods.

In my opinion, it must be done by Factorio side itself, just merge all same ingredients together, but with message in the log file, that this mod must be written more carefully.

In my opinion, it must be done by Factorio side itself, just merge all same ingredients together, but with message in the log file, that this mod must be written more carefully.

Agreed.

That's pretty much what I'd do in my library, do the check, put a message in the log for every error found, shame I you can't identify which mods add to a recipe while loading. Put it on a mod setting so you can turn it on/off.
If I do it like my Redundant Technology Prerequisites check though, it shouldn't slow things down too much. (For most people it takes about half a second. But the earlier version, for some people it was taking more than 5 minutes)