Just an FYI because you are using defines.flow_precision_index.one_second. See https://forums.factorio.com/viewtopic.php?p=538301#p538301.
In order to be compatible with <1.1.25 and >=1.1.25 you can change it to precision_index = defines.flow_precision_index.one_second or defines.flow_precision_index.five_seconds,

I created a pull request with this change after confirming it works: https://github.com/IshFx/spawner-alert/pull/5

Thanks both of you for the report and the PR, i'll merge it asap.

Edit: should be fixed in 0.1.8.

By the way, if you are using semantic versioning and this is a stable mod, this really should be 1.x.x or later.

Granted, Wube clearly isn’t: they introduced breaking API changes in a patch release!

Semver allows 0.x.x releases :) It just says you can do what you like in them!

The FAQ says you should go to 1.0 as soon as users depend on it and it is stable.

I’ve been trying to improve this particular aspect of SemVer for a bit now: https://github.com/semver/semver/issues/333#issuecomment-626190938

If that change gets incorporated into SemVer 2.1, it’d make early versions of software a lot better to work with. It reflects the reality of how most developers work already, as evidenced by Factorio itself.

Interesting stuff, but in this case I think it is a bit of a non issue. There's no reason why this 'random' factorio mod has to use semver, and it is perfectly normal for projects like this to use 0.x.y versioning.

I've been thinking about going 1.0.0 for a while ... i might do it for the next release.