Providing a useful message for startup errors

[Coppermine]

I recall once when I installed a mod and tried to launch Factorio I got an error from that mod during startup (the data*.lua phases) from that mod along the lines of "I noticed you have this other incompatible mod installed; you shouldn't use us both at the same time".

That was very helpful. Now I find myself wanting to do the same with a mod of my own -- that is, provide a useful error message when I detect a fatal configuration issue during startup, and thus pre-empt a load failure with a less useful error that would otherwise occur.

Unfortunately I can't remember in which mod I originally saw this feature, and I can't find anything that would achieve this in the documentation (it's entirely possible I just missed it). Can anyone suggest how to do it?

[darkfrei]

Just adding to info.json

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"dependencies": [
  "base >= 0.15.0",
"  ? mod_name < 0.0.0"

- negative version is not exists, incompatible.

[Coppermine]

Thanks, but the mod incompatibility was just an example. My situation is more complex than that; I need to be able to run arbitrary code in data*.lua and report an error if I detect a problem.

[posila]

In data*.lua you can call error("there seems to be a problem")

[Coppermine]

In data*.lua you can call error("there seems to be a problem")

Perfect! Thanks .

[Rseding91]

0.16 also adds incompatible dependencies so in 0.16 you can do this:

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"dependencies": [
"base >= 0.15.0",
"! mod_name"]

and it will trigger your mod to simply be disabled at startup until the given mod is either removed or disabled.